What does flextime typically allow employees to do within a standard workweek?

Question $32$ options:

a$)$

Paying certain employees for working extra time throughout a five$-$day workweek as incentives

b$)$

Allowing employees to take a certain number of leaves throughout the year as a reward system

c$)$

Permitting certain employees to select convenient days to work, irrespective of the five$-$day workweek

d$)$

Permitting certain employees to select different starting and ending times within a five$-$day workweek