Select the most appropriate option that can substitute the highlighted segment in the given sentence.
She is strictly advised to be on bed for three weeks lest she would fall sick again.

Correct option is D

The correct substitution of the highlighted segment is (d) "lest she should fall sick again." The use of "lest" to express a preventative caution requires the modal verb "should" to follow it, creating a subjunctive mood that indicates a precaution against a potential outcome. Grammatical rule used: "Lest" is followed by "should" plus the base form of the verb to express a condition or possibility to be avoided. Example: She carried an umbrella, lest she should get wet in the rain.