Select the most appropriate option to substitute the highlighted segment in the given sentence.
She has been studying for two o’clock.

Correct option is B

The correct substitution is "studying since two o’clock."
Explanation: The word "since" is used to refer to a specific point in time in the past, indicating when the action started.
"For" is used to refer to a duration (e.g., "for two hours"), which is not applicable here.
The continuous tense "has been studying" suggests an ongoing activity that started in the past and continues up to the present.
Grammatical Rule: Use "since" to indicate the starting point of an action that is still ongoing in the present perfect continuous tense.
Example: She has been studying since morning.
Comparative Table

Examples Comparing "Since" and "For"
1. Present Perfect Tense:
· I have been living here since 2010. (Starting point: 2010)
· I have been living here for 13 years. (Duration: 13 years)
2. Present Perfect Continuous Tense:
· He has been working since this morning. (Starting point: this morning)
· He has been working for 6 hours. (Duration: 6 hours)