The word abstruse describes something that is difficult to understand or obscure.
In the given sentence, the speaker's style was abstruse, which caused the students to become disinterested and fidgety. This implies the style was hard to comprehend.
Comparing the options, recondite most closely matches the meaning of abstruse, as both refer to something hard to understand.
Each item in this section consists of a word in capital letters followed by four words or groups of words. Select the word or groups of words that is most similar in meaning to the word in capital letters.
AMBIGUOUS
Each item in this section consists of a word in capital letters followed by four words or groups of words. Select the word or groups of words that is most similar in meaning to the word in capital letters.
ELUCIDATE
Each item in this section consists of a word in capital letters followed by four words or groups of words. Select the word or groups of words that is most similar in meaning to the word in capital letters.
MONOTONOUS
Each item in this section consists of a word in capital letters followed by four words or groups of words. Select the word or groups of words that is most similar in meaning to the word in capital letters.
KINDLE
Each item in this section consists of a word in capital letters followed by four words or groups of words. Select the word or groups of words that is most similar in meaning to the word in capital letters.
PALATIAL