We Have Five Fingers Because We Have Descended from a Devonian

Multiple Choice

We have five fingers because we have descended from a Devonian fish that had five phalanges or bones in its fins. (Carl Sagan, Cosmos)
This statement is made up of a(n) _____ and a(n) _____.

A) nonargument; explanation
B) argument; conclusion: We have five fingers
C) nonargument; unsupported assertion
D) argument; conclusion: We have descended from a Devonian fish that had five phalanges or bones in its fins