The argument says that rain is more prevalent in plains than in other regions of Spain. Flowers tend to grow more thickly where rain is plentiful.
Looks like a direct inference.
So we can say flowers grow more thickly in plain than in other regions of Spain.
A. The hills and mountain ranges of Spain are devoid of flowers of any kind -
Rain affects only the thickness of flowers. This line is a stretch.B. Flowers grow more thickly in the plains of Spain than on its mountain ranges -
Yep, we got exactly what we wanted.
C. Rain plays a vital role in Spain's diverse ecosystem -
Based on the above argument we cannot comment on a diverse ecosystem. D. A recent research has shown that rain and the existence of both flora and fauna are closely related- Again out of context.
E. Animals find it hard to survive in Spain's hilly areas, since they need plants for nourishment and these are more scarce in this kind of topography in Spain -
Dump this as we don't have a clue about animals in Spain. So we cannot infer this.Therefore,
option B is our answer.