Fill in the blank with the most suitable verb:
Maria isn't studying hard but I ________.
A verb is used to express an occurrence, action, or state. It is the grammatical centre of the predicate in a sentence.
An auxiliary verb is a verb which gives is used in the formation of tenses, moods, tones, etc.
Option C is correct as the isn't studying indicates the use of present continuous tense and therefore, has and have cannot be used.
The other options are wrong as the subject is I and the sentence is in the present continuous tense.
The correct answer is C)am