She should be ashamed ________ her actions. (a) by (b) at (c) of (d) in
She should be ashamed of her action.
Of is a preposition which used to indicate relating to, belonging to, to indicate reference, to refer a period.
E.g:
He will be available here from 9 to 10. ( to refer to a period )
Shyam has also dreamed of being famous. ( to indicate relating to, belonging to)
This is the picture of her last birhday.(Indicating reference)