The sentence is divided into four segments: (A), (B), (C), and (D). Identify the segment that contains a grammatical error. If the sentence is
both grammatically and contextually correct, select“No error” as the correct answer.

He had scarcely (A)/ stepped out of the (B)/ house than it began (C)/ to rain heavily. (D)

The correct option is C.

Let us analyze the grammatical structure of the sentence step-by-step:
The sentence is: "He had scarcely (A)/ stepped out of the (B)/ house than it began (C)/ to rain heavily. (D)"

1. Correlative Conjunction Rule: In English grammar, adverbs that denote a very short duration or immediate succession of events, such as scarcely, hardly, and barely, must be paired with the conjunction when or before.
2. The use of 'than': The conjunction than is comparative and is strictly paired with no sooner (for example: "No sooner had he stepped out... than it began..."). Using "than" with "scarcely" is a grammatical error.
3. Identifying the Error: In the given sentence, segment (A) contains "scarcely", but segment (C) introduces "than" ("house than it began"). This incorrect pairing forms the grammatical error.
4. Corrected Sentence: Replacing "than" with "when" resolves the error. The correct sentence is: "He had scarcely stepped out of the house when it began to rain heavily."

Therefore, segment (C) contains the grammatical error.