IELTS Reading passage issue (English as a foreign language learner I am)

Solution 1:

Tests which require a "true / false / not given" answer should not be ambiguous, nor should they require students to make assumptions...

If the examiners wanted to know what students could "infer" from the given text, they would not have asked for a "true / false / not given" answer.

A person's ability to differentiate between "most diverse" & "most numerous" is a credit to their understanding of the language & to their intelligence...

Teachers who put ambiguous questions in "yes / no" type tests are either ignorant or sadistic.

Regarding the question quoted by Isakov-U, the correct answer would be (/ should be) "not given".