Tricky one. Of the given sentences, both A and D relate to the vibrations produced by elephants as they trumpet. Sentence A describes how the high-frequency vibrations travel in air, and D, how low frequencies travel through the ground. D follows A. Consider sentence B. What does this relate to? B could follow C, as it adds to the idea of a "two-tiered communication model" providing an effective way of sending messages to herd members and rival herds. Equally, B could follow D. The fact that low frequency vibrations travel through the ground is useful in the jungle, where there is dense vegetation. So, let us consider the order CBAD. This does not make a cogent paragraph, as it is not clear from the first sentence-- C --what the "herd members" or "distant herds" refer to. Also, B, which follows C, does not explain what the herd referred to in C is. The transition from B to AD is abrupt. On the other hand, ADBC sounds more natural. A and D describe how elephants communicate in high and low frequency vibrations, B explains how this is useful in a jungle, and C adds to B, summing up the paragraph. When arranged this way, there is no ambiguity in what the 'herd' refers to. So, this is the right order. Correct Answer: ADCB
All features of the online course, including the classes, discussion board, quizes and more, on a mobile platform.
Download videos onto your mobile so you can learn on the fly, even when the network gets choppy!