A part of the sentence is underlined. Choose the alternative that best improves the underlined part, or select "No improvement" if the sentence is already correct: "No other snake is as poisonous as this one."

Introduction / Context:
This sentence improvement question examines your understanding of comparative structures and the use of "as...as" in English. The sentence "No other snake is as poisonous as this one" uses a negative combined with the positive "as...as" construction to make a comparison. You must determine whether this structure is already correct or whether one of the alternatives improves it.

Given Data / Assumptions:

- Original sentence: "No other snake is as poisonous as this one." - Underlined part: "is as poisonous as this one". - Options: "are as poisonous as this one", "is more poisonous as this one", "is poisonous than this one", "No improvement". - The intended meaning is that this snake is at least as poisonous as any other snake, implying that no other snake exceeds it in poisonousness.

Concept / Approach:
The pattern "No other + singular noun + is as + adjective + as + this one" is a standard way to express that something is the highest in degree for that quality. The singular subject "No other snake" correctly takes the singular verb "is". The double "as" construction is correct; problems arise only if we mix it with "more" or "than". Therefore, the original structure is grammatically sound and consistent with typical comparative usage.

Step-by-Step Solution:
Step 1: Check subject verb agreement. The subject is "No other snake" (singular), so the correct verb is "is". Option A, "are as poisonous as this one", would be wrong because "are" is plural. Step 2: Examine the comparative structure. "As poisonous as" is the correct form for equality comparison. It should not be combined with "more" or "than". Step 3: Evaluate option B: "is more poisonous as this one". This incorrectly mixes "more" with "as"; the proper pattern is "more poisonous than", not "more poisonous as". Step 4: Evaluate option C: "is poisonous than this one". This omits "more" before "poisonous" and incorrectly uses "than" with a positive adjective only. Step 5: Review the original: "No other snake is as poisonous as this one." It maintains subject verb agreement and uses "as...as" correctly. Step 6: Conclude that there is no grammatical or structural error, so "No improvement" is the correct choice.

Verification / Alternative check:
Compare similar sentences that express the highest degree: "No other city is as crowded as this one", "No other student is as diligent as Rohan". These are standard and grammatically correct. The pattern expresses that the named item is at the top level of that quality. If we tried "No other city is more crowded as this one", it would sound wrong for the same reasons that make option B unacceptable. This confirms that the original structure is correct.

Why Other Options Are Wrong:
Option A introduces a plural verb "are" for a singular subject, breaking subject verb agreement. Option B mixes two different comparative patterns, "more...than" and "as...as", which is incorrect; we never say "more poisonous as". Option C uses "than" without "more" or "less", which is also incorrect; "poisonous than" must be preceded by a comparative word like "more". Hence, all three alternatives contain clear grammatical errors.

Common Pitfalls:
Candidates sometimes feel that a negative and a positive comparison structure together must be wrong and try to "improve" sentences that are already correct. For superlative meaning, both "No other snake is as poisonous as this one" and "This snake is more poisonous than any other snake" are acceptable. The exam often tests whether you can recognise a correct structure and confidently select "No improvement" instead of changing it unnecessarily.

Final Answer:
No improvement is required; the sentence "No other snake is as poisonous as this one" is correct.