Read the following sentence.
"Hearing the knock, she opened the door."
What kind of synthesizer is the underlined word in the sentence ? It is _________.

The correct answer is Option B (a participle).

Key Points:
• Core Language Concept Tested: The question tests the candidate's understanding of Non-Finite Verbs, specifically the distinction between gerunds and participles. (Note: The word 'synthesizer' in the official question paper appears to be an unusual typographical artifact intended to mean 'syntactic element' or 'modifier').
• Why the Correct Option is Right: The official answer key marks option 2 as correct. This is absolutely accurate. In the phrase "Hearing the knock", the word "Hearing" is a present participle (a verb ending in -ing that functions partially like an adjective). It creates a participial phrase that modifies the subject "she", describing what she was doing at the moment she opened the door.
• Common Exam Traps and Pitfalls: MPSC often preys on the confusion between gerunds and present participles since both end in '-ing'. A common mistake is selecting 'gerund' (option 1). However, a gerund acts purely as a noun (e.g., 'Hearing is a sense'), whereas here, it describes the subject's concurrent action.
• Elimination of Incorrect Options: It is not a clause (adverbial or noun) because it does not contain a subject and a finite verb. Between gerund and participle, its modifying function dictates it is a participle. Thus, by strict syntactical analysis, we arrive safely at the correct choice.
• Preparation Strategy: For future exams, practice distinguishing '-ing' words by testing if they act as nouns (gerund) or adjectives/continuous actions (participle).
• Key Takeaway: Remember: An '-ing' verb acting as a modifier to a subject is a present participle, while one acting as a noun is a gerund.