Refer to the cladogram shown above. the
numbers 1 through 5 represent species that
exist today. what's the most recent common
ancestor of species 1 and 4?
6.
a. d
b. c
c. b
d. a

The correct answer is B.C

Explanation:

A cladogram is a diagram used to show the evolutionary relationship between different species and used to find out their most common recent ancestor that means from whom they are evolved or descended.  

Each node represents the common ancestor which descends into two branching lines. These two branching line shows the two descendants from the same common ancestor. So each node represents the common ancestor.  

Therefore in this question, C is the most recent common ancestor for species 4 and A is the most recent common ancestor for species 1 but A and B is can not be an ancestor of species 4 because number 4 species have descended earlier than 3, 2, and 1 species as shown in the cladogram.

As number 1 species is the last descendent so it has all A,B, C and D as its common ancestor but 4th species has only C and D as its common ancestor. So as C is the most common recent ancestor of species 4, therefore, the most common recent ancestor for species 1 and 4 is C.  

Therefore the correct answer is B.C

the most logical answer would be a