Which is an example of a vestigial structure?
a. fish gills
b. human arm
c. raccoon tail
d. whale pelvis bone

D. Whale Pelvis Bone

Explanation:Structures that have no apparent function and appear to be residual parts from a past ancestor are called vestigial structures.

Examples of vestigial structures include the human appendix, the pelvic bone of a snake, and the wings of flightless birds. Hope this helps

the correct answer is 4) heat and pressure

metamorphic rocks arise from transformation of existing rocks types, in a process called metamorphism. during metamorphism the original rock(prolith) change into metamorphic rock by heating (150-200c) and pressure of more than 1000 bar. the original rock can be sedimentary, igneous, or existing metamorphic rock.