Meaning of off sick

[Rich7]

Test No. incompl/inter-95 "Letter of Complaint (2)", question 10

since there were a number of people ......... sick.

(a) through
(b) for
(c) off
(d) under

Test No. incompl/inter-95 "Letter of Complaint (2)", answer 10

since there were a number of people off sick.

Correct answer: (c) off

Your answer was: incorrect
since there were a number of people under sick.
_________________________

because they are sick they got the day off, Am I right?

[Torsten]

Yes, they were absent from work because of sickness.

TOEIC listening, photographs: The bund Shanghai