Which sentence uses the past tense of to study correctly? A. Mark is studying for his math test with Margie. B. Mark will study for his math test with Margie. C. Mark studied for his math test with Margie.

The correct answer is C, "Mark studied for his math test with Margie"

Explanation: The past tense is used when you want to talk about an event that had already happened in the past. That being said, an conjugation of the verb STUDY is the following:

I study: Present I studied: Past simple I will study: Future

There we can see that the past of the verb Study is studied and for that reason, the only option that has it correctly is C.

C. Mark studied for his math test with Margie. This is the correct option.

"To study" is the infinitive and when this is used in the past, the final "y" turns into "i" and then the suffix "ed" is added.

These options are wrong:

A. Mark is studying for his math test with Margie. This is an instance of present continuous and the verb "to study" is in the present participle.

B. Mark will study for his math test with Margie. This is an instance of simple future, so the verb " to study" is in the bare infinitive.