(A) This answer choice is incorrect as it repeats the original sentence 

(B) This answer choice introduces the plural pronoun “those” that does not have an antecedent. Note that this plural pronoun cannot refer to the singular noun “the body mass.” Further, the plural noun “hippopotamuses” is inconsistent with the singular noun “rhinoceros,” further contributing to the faulty comparison in this sentence. 

(C) While this answer uses the correct relative pronoun “that” and draws a logical comparison between “the body mass” of the two animals, it introduces the incorrect double possessive construction “of hippopotamuses’.” Additionally, the plural noun “hippopotamuses” is inconsistent with the singular noun “rhinoceros,” thus disrupting parallelism in this comparison. 

(D) CORRECT. This answer choice draws a logical comparison between “the body mass of the white rhinoceros” and “that of the African hippopotamus.” Furthermore, the pronoun “that” clearly and unambiguously refers to its antecedent, “the body mass.” Finally, the singular noun “white rhinoceros” is parallel to another singular noun “African hippopotamus.” 

(E) This answer choice incorrectly compares “the body mass of the white rhinoceros” to “the African hippopotamuses” rather than to “the body mass” of “the African hippopotamus.” Further, the plural noun “hippopotamuses” is inconsistent with the singular noun “rhinoceros,” thus disrupting parallelism in this answer.