Anatomical homology in vertebrate forelimbs is considered to be evidence for evolution because: 1. differences among vertebrate forelimbs suggest that they evolved independently. 2. the anatomy of the vertebrate forelimb is not currently under natural selection. 3. similarities among vertebrate forelimbs suggest that they evolved from a common ancestor. 4. such homologies do not exist in other areas of the vertebrate skeleton. 5. similarities among vertebrate forelimbs suggest that they have evolved convergently

Answer :3. similarities among vertebrate forelimbs suggest that they evolved from a common ancestor.

Explanation:

The study of differences and similarities in the anatomy of different species is comparative anatomy. It is based on the concept that  

1.)Homologous structures  which are present in different species, because they have a common decent and must have evolved  divergently from a shared ancestor. Theses anatomic structures may not be used for the same purposes. For example the forelimb of fox and whale.

2. Some  structures (Analogous)which are similar in different organisms must have evolved  ,(acquired through natural selection) through convergent evolution in similar environment,  and not inherited from a recent ancestor. These organisms usually use these structures for a common purpose. For example the streamline body shape   of shark and porpoises, which though are used for a common purpose of swimming, were inherited from different ancestors.

.  Example  of comparative anatomy is the common  bone structures in forelimbs of fox, whales, bats, and humans. These appendages is made up of  the same basic parts; despite serving  different functions.  

Comparative anatomy helps scientists in classification of organisms based on their similar characteristics of their anatomical structures.

3. similarities among vertebrate forelimbs suggest that they evolved from a common ancestor

Explanation:

Homologous structures (i.e. organs) are structures that can differ in function, but are similar in form because they came from the same common ancestor.

Observing homologous organs in different taxa means that those  taxa come from a common ancestor that possessed such structure. It means that this structure throughout evolution adapted to different lifestyles (in thedifferent taxa) and acquired different functions.

Forelimbs of vertebrates is a common example of homology where  wings (i.e. bats), arms (i.e. primates),   front flippers (i.e. whales) and  forelegs (ie. horses) are all derived from the same ancestral  structure (tetrapod  ancestor).

straight or amphibians are homeothermic to thermal