What's a major assumption when drawing evolutionary relationships between organisms?

Based on DNA sequences, it is believed that changes in nucleotide sequence between two species are equivalent to the time that has elapsed since the two species diverged from their common ancestor. Gene sequencing is being used in addition to morphology to determine evolutionary relationships between organism. Homologous sequences show greater evolutionary relationship

i am positive it is c. condensing but i may be wrong

i took a test for bio that had this question and these were the correct answers, not sure if this is any now lol

the nervous system and the muscular system work together.  

sweat reaches the surface of the skin and evaporates into the air.

muscles underneath the skin relax, causing hair on the skin to lay flat.