This pen . . . . . . . . me Rs. 10.

costed
costs
cost
will cost

The correct answer is C. cost.

The verb “cost” is used to describe the price of something. It is typically used in the simple past tense, as in “This pen cost me Rs. 10.” However, it can also be used in the present tense, as in “This pen costs me Rs. 10.”

The verb “costed” is not a standard English word. It is sometimes used as a past tense form of “cost,” but it is not considered to be grammatically correct.

The verb “will cost” is used to describe the price of something in the future. It is typically used in the simple future tense, as in “This pen will cost me Rs. 10.”

I hope this helps!