This question tests the concept of parallelism & subject verb agreement. Scientist are confirming that there are two causes, human expansion and human appropriation, of species extinction. They are connected by 'and' & requires parallel structure. Similarly 'X and Y' is a plural subject.

A. expansion and the human appropriation of Earth’s finite resources is
Parallelism error & S-V agreement error

B. expansion and human appropriation of Earth’s finite resources are
Correct answer

C. expansion and its appropriation of Earth’s finite resources is
S-V agreement error

D. expansion, along with their appropriation of Earth’s finite resources, is
Distort the meaning, further "human" is used as adjective here, so 'their' may refer the scientist, which is nonsensical

E. expansion, along with its appropriation of Earth’s finite resources, are
Distort the meaning, its has no antecedent and S-V error