An organism's development from an embryo may contain clues about its history that scientists can use to develop relationships and build evolutionary trees. Ancestral characters are often preserved in an organism's developmental stages. For example, both bird and human embryos go through a stage where they have slits and arches in their necks like the gill slits and gill arches of fish. These structures are not gills and do not develop into gills in birds and humans, but because they are so similar to gill structures in fish at this point in development scientists believe that A) birds and humans evolved from fish. B) all vertebrate animals have identical embryos. Reactivate C) fish, birds, and humans share a common ancestor. D) fish evolved as a life form long before birds or humans.

Answer is option "C"

Explanation:

The way that these formative highlights are so like the gill structures in fish bolsters that fish, chicks, and people share a typical predecessor Ancestral characters are regularly, however not constantly, safeguarded in a life form's improvement. For example, both chick and human early creatures experience a stage where they have cuts and bends in their necks like the gill cuts and gill bends of fishThese structures are not gills and don't shape into gills in chicks and individuals, be that as it may, how they are so similar to gill structures in fish currently being created support that chicks and individuals share a run of the mill ancestor with fish. Subsequently, formative characters, alongside different lines of proof, can be utilized for developing phylogeniesHence, the right answer is option C "fish, birds, and humans share a common ancestor"

Mantle convection  is the slow  creepingmotion of earth's solid silicate  mantle  caused by  convection  currents carrying  heat from the interior  to the planet's surface.[1][2]  the earth's surface  lithosphere, which rides atop the  asthenosphere  (the two components of the  upper mantle), is divided into a number of  plates  that are continuously being created and consumed at their opposite  plate boundaries. accretion occurs as mantle is added to the growing edges of a plate, associated with  seafloor spreading. this hot added material cools down by  conduction  and  convection  of heat. at the consumption edges of the plate, the material has thermally contracted to become dense, and it sinks under its own weight in the process of  subduction  usually at an  ocean trench.[3]this subducted material sinks through the earth's interior. some subducted material appears to reach the lower mantle,[4]  while in other regions, this material is impeded from sinking further, possibly due to a phase transition from  spinel  to  silicate perovskiteand  magnesiowustite, an  endothermic reaction.[5]the subducted oceanic crust triggers  volcanism, although the basic mechanisms are varied. volcanism may occur due to processes that add buoyancy to partially melted mantle causing an upward flow due to a decrease in density of the partial melt.secondary forms of convection that may result in surface volcanism are postulated to occur as a consequence of intraplate extension[6]  and  mantle plumes.[7]it is because the mantle can convect that the  tectonic plates  are able to move around the earth's surface.[8]mantle convection seems to have been much more active during the  hadean  period, resulting in gravitational sorting of heavier molten  iron, and  nickel  elements and  sulphides  in the core, and lighter  silicate minerals  in the  mantle.