ERROR SPOTTING — Identify the part (A–E) that contains a grammatical, usage, or spelling error. If there is no error, choose E (All correct). Sentence (split into parts): A) He had experienced B) a purposefully C) discussion on topics of our D) interest

Introduction / Context:
This question checks correct word form (adjective vs adverb) inside a noun phrase and general sentence cohesion. The focus is on whether the modifier before the noun 'discussion' is in the right form.

Given Data / Assumptions:

• The intended meaning is that the discussion had a clear purpose.
• Segment B uses the adverb “purposefully”.
• Segment C introduces the head noun “discussion”.
• Standard English noun phrases typically use adjectives (not adverbs) before nouns.

Concept / Approach:
Before a noun, we need an adjective such as “purposeful”, not the adverb “purposefully”. The correct sequence is “a purposeful discussion…”. The remaining parts form a coherent prepositional extension “on topics of our interest”.

Step-by-Step Solution:
1) Identify the head noun: discussion.2) Check the modifier form: “purposefully” (adverb) is incorrect before a noun.3) Replace with adjective: “purposeful”.4) Reconstruct: “He had experienced a purposeful discussion on topics of our interest.”

Verification / Alternative check:
Adverb placement test: adverbs typically modify verbs, adjectives, or other adverbs, not nouns. If we wanted an adverb, it would modify a verb like “spoke purposefully”.

Why Other Options Are Wrong:
A) Verb phrase fragment is fine; past perfect is acceptable contextually.C) Correctly introduces the noun “discussion”.D) “interest” appropriately completes the prepositional phrase.E) Not applicable because B contains an error.

Common Pitfalls:
Confusing “purposeful” (adjective) with “purposefully” (adverb). In error-spotting, check part of speech against position.

Final Answer:
B (Use “a purposeful”)