Select the most appropriate option to fill in the blank.

Ritu had gone out to drink water _______________ her examination started.

before

The most appropriate option to fill in the blank is before.

The sentence is about how Ritu had gone out to drink water before her examination started. The word "before" is the most accurate preposition to use in this context, as it indicates that Ritu went out to drink water before her examination started.

The other options are not as appropriate.

• Even means "though" or "despite." This does not make sense in the context of the sentence, because Ritu did not go out to drink water even though her examination was starting.
• Whether means "if." This does not make sense in the context of the sentence, because Ritu did go out to drink water, it is not a question of whether she did.
• Now means "at the present time." This does not make sense in the context of the sentence, because Ritu went out to drink water before her examination started, she is not going out to drink water now.