Select the most appropriate option fill in the blank.
I have been studying this course ______ two years now.

Correct option is C

The correct option to fill in the blank is (c) for.
Explanation: “For” is used to refer to a period of time. Since “two years” is a duration, “for” is appropriate.
Grammatical rule used: Use “for” + period (for 2 years), “since” + point in time (since 2020).
Example: I have lived here for five years.
Explain why other options are incorrect:
· (a) through: means ‘by way of’ (के माध्यम से), incorrect for time.
· (b) since: needs a starting point (e.g., since 2020), not a duration.
· (d) almost: is an adverb, not a preposition.