Select the most appropriate option for the given blank.
She _____________ for hours while the train rolled on.

The correct answer is (b) slumbered.
Explanation: The past tense "slumbered" is used to describe an action that occurred in the past while the train continued moving.
· Had slumber: Incorrect, as "had" requires the past participle "slumbered."
· Slumbers: Incorrect, as it is in the present tense.
· Has slumbered: Incorrect tense, as it indicates an action completed recently.
Correct sentence: "She slumbered for hours while the train rolled on."