Select the most appropriate option that can substitute the underlined segment in the given sentence. If there is no need to substitute it, select ‘No substitution’.
Because I had to catch the train, and as we were short on time, I forget to pack my toothbrush for our vacation.

A

No substitution

B

I have forget to pack my toothbrush for our vacation

C

I forgot to pack my toothbrush for our vacation

D

I have forgot to pack my toothbrush for our vacation