The correct option is E To suggest that the elephant is descended from an aquatic animal and that its trunk originally evolved
There is a lack of parallelism ( a balance is achieved within one or more sentences by using elements in the sentence that are grammatically similar in structure, sound and meaning. It is used to balance noun with noun, prepositional phrases with prepositional phrases, participles with participles) in the given sentence. We notice that the use of 'is descended', a verb and 'evolving', a participle do not work together. Options A, B ('descended' and 'evolving), and C ('had descended' and 'evolved') lack parallelism. D uses past tense to describe the situation of someone in the present that had ancestors in the past which is incorrect - here, present tense should be used. Now, we notice that option E rectifies the original errors and does not create errors of its own. Thus, option E is our answer.