Question

Fill in the blank with the most appropriate word.
I was quite astonished ______his quick reaction.

• A. with
• B. of
• C. at
• D. on

Answer 1

Answer: (C)

at

Option C is the correct answer because 'at' is used with adjectives to show the cause of something.

Options A, B and D are incorrect because the prepositions 'with' is used to indicate being together or being involved, 'of' is used for belonging to, relating to, or connected with and 'on' is used to express a surface of something or place or location.