The following sentence has been split into four segments. Identify the segment that contains a grammatical error.
(A) They carefully planned the surprise party, / (B) ensuring everything / (C) was perfect for their friend, / (D) who thoughtful celebrated their birthdays.

Correct option is B

Option (b) contains an error.
· Explanation: Segment D: “who thoughtful celebrated their birthdays” is grammatically incorrect. The issue lies with the word “thoughtful,” which is an adjective, but an adverb is required here to describe the verb “celebrated.”
· The correct adverb form is “thoughtfully.” So the corrected segment should read: “who thoughtfully celebrated their birthdays.”
Grammatical rule used:
· Adjectives describe nouns, while adverbs describe verbs, adjectives, or other adverbs.
· Since “celebrated” is a verb, we need an adverb to modify it.
Explanation in Hindi:
· “Thoughtful” एक विशेषण है, जो संज्ञा की विशेषता बताता है। लेकिन यहाँ “celebrated” क्रिया है, और क्रिया की विशेषता बताने के लिए क्रिया विशेषण (adverb) चाहिए—इसलिए “thoughtfully” सही शब्द होगा।
Example:
· Incorrect: She thoughtful replied to the message.
· Correct: She thoughtfully replied to the message.