English grammar — Spot the error (choose the segment that contains a grammatical error; choose ‘‘No error.’’ if the sentence is correct). Sentence: Looking forward to seeing you soon.

Introduction / Context:
This is an error-spotting task. You must identify the part of the sentence that contains a grammatical or usage error. If all parts are acceptable in contemporary written English, select ‘‘No error.’’

Given Data / Assumptions:

• The sentence is intended as a courteous closing line, such as in an email or message.
• Elliptical closings (without an explicit subject and finite verb) are acceptable in such contexts.
• “Look forward to” requires a noun or gerund (verb + ing) after the preposition “to.”

Concept / Approach:
Check common problem areas: verb patterns after prepositions, pronoun case, and whether fragments are acceptable as closings. In professional correspondence, phrases like “Looking forward to hearing from you” are idiomatic and correct.

Step-by-Step Solution:

Verification / Alternative check:
The full, non-elliptical version would be: “I am looking forward to seeing you soon.” The shortened version used in closings is standard and correct.

Why Other Options Are Wrong:

• A/B/C/D are acceptable and do not introduce a grammatical error here.

Common Pitfalls:
Assuming that every sentence must have an explicit subject and finite verb. In email closings and notes, elliptical structures are widely accepted and grammatically defensible.

Final Answer:
No error.