Question

why do sand cats purr but lions roar? researchers hypothesize that this difference between the two feline species may be partly due to a u - shaped bone in their throats called the hyoid. sand cats, which are much smaller than lions, have a rigid hyoid that rumbles when the cat’s larynx vibrates, resulting in a purr. by contrast, lions have a somewhat flexible hyoid, and the bone is attached to the skull with a stretchy ligament that sand cats lack. these traits allow lions and most other species of big cats to produce powerful roars. the same traits may also prevent most big cats from purring.
10 mark for review
which choice best describes the overall structure of the text?
a the text presents a theory about two species, then discusses facts that weaken it.
b the text compares the habitats of two species, then explains how those habitats are changing.
c the text describes a behavior shared by two species, then discusses other behaviors shared by them.
d the text poses a question about two species, then presents a possible answer.

Explanation:

The text opens with a question: why sand cats purr but lions roar? It then presents researchers' hypothesized answer, linking the difference to the structure of their hyoid bones and how this relates to their vocal behaviors. Option A is incorrect because no facts weaken the theory. Option B is incorrect as habitats are not discussed. Option C is incorrect because the text focuses on a differing behavior, not shared ones.

Answer:

D. The text poses a question about two species, then presents a possible answer.