4. what must be true about an index fossil whose absolute age is used as a reference for other fossils?
the absolute age of the index fossil is actually unknown.
the absolute age of the index fossil was determined only by relative dating.
the absolute age of the index fossil was determined by radioactive dating or another absolute method.
the index fossils must be the same age as the other fossils.

Will mark brainliest if correct/available! which of the following statements is true? all plants need flowers to sexually reproduce. sexually reproduced offspring are identical to their parents. fertilization always occurs inside the female's body. a body cell has twice the number of chromosomes as an egg cell.

Models are non-visual ways of coummincating how someone thinks about something in the natural world

Hydrilla (hydrilla verticillata) is an invasive aquatic plant and one of the most serious aquatic pests in florida. hydrilla has already been introduced to hundreds of bodies of water throughout florida, hydrilla is difficult to control because it grows rapidly and survives in many different water depths and conditions. hydrilla • describe how hydrilla affects native plant and animal species. include both a biotic and an abiotic limiting factor. • suggest one biotic and one abiotic recommendation that could slow the spread of hydrilla