Çözüldü Vocabulary for TOEFL iBT

He tried to ______ the sinking morale of his friend in the hospital.

A) sustain
B) foster
C) bolster
D) nourish
E) exacerbate

Correct Choice: C (bolster)

Official Explanation:
If the friend has a “sinking morale,” this means that the friend’s feelings or attitude are overwhelmed or defeated. The speaker would, thus, want to raise or bolster this morale. Choice a, b, and d are all incorrect. The speaker would not want his friend’s morale to continue to sink.

Note: "Exacerbate" means to make (a problem, bad situation, or negative feeling) worse. (from Google)

TOEFL iBT Vocabulary
https://en.ru1lib.org/book/732135/8c17d0
[Page 28 (36 in the pdf file), Question: 22, Answer and Explanation on page 30 (38 in the pdf file)]