In this English vocabulary and sentence improvement question, you are given the definition To emend a piece of writing means to remove mistakes from it, where the underlined phrase remove mistakes from it may be replaced by a single precise verb. Choose the option that best matches the meaning of emend in the context of written text and produces a concise and accurate sentence, and choose No improvement only if the original wording is already ideal.

Introduction / Context:
This question tests understanding of a specific vocabulary item and the ability to replace a descriptive phrase with a precise verb. The sentence gives a definition of emend in relation to a piece of writing and asks you to identify the best single word equivalent for remove mistakes from it. Examinations often include questions where a longer explanation can be replaced by an exact verb, and the challenge is to select the word that matches the technical nuance of the term emend in the context of written text.

Given Data / Assumptions:

• The base statement is To emend a piece of writing means to remove mistakes from it.
• The underlined phrase is remove mistakes from it.
• The options offered are amend, edit, rephrase, and No improvement.
• The focus is on the meaning of emend as used in reference to written material.

Concept / Approach:
The verb emend is closely related to amend and has the specialised meaning of correcting errors in a text, often by making scholarly or careful changes. Amend in the context of writing means to make improvements, usually by correcting mistakes or updating content. Edit, while also connected, covers a broader process that includes arranging, selecting, and preparing material for publication, not just removing mistakes. Rephrase means to express the same idea in different words, which does not necessarily involve error correction. Therefore, the approach is to find the verb that is closest in core meaning to emend, which is amend.

Step-by-Step Solution:
First, focus on the key idea that emend involves making corrections to a written text. Second, evaluate amend and recall that in many formal contexts it means to correct or improve a document, law, or piece of writing. Third, consider edit and note that it includes a wide range of operations beyond simple correction, such as cutting, rearranging, and sometimes rewriting material. Fourth, examine rephrase and see that it deals with expressing content differently without necessarily fixing errors. Fifth, conclude that amend is the closest match to the core process of removing mistakes and improving accuracy in a text.

Verification / Alternative check:
To verify, you can look at typical uses in dictionaries and style guides. Emend is often defined as to correct or improve a text, especially by removing errors. Amend is defined as to make changes in order to correct or improve, particularly in documents and laws. A book editor might emend a manuscript by amending certain lines or passages. Edit, although related, describes the whole process of preparing material for publication, and a person can edit a text without personally emending every small error. Therefore, amend as a replacement for remove mistakes from it gives a tighter, more precise definition of emend.

Why Other Options Are Wrong:
Option B, edit, is too broad, since editing involves selection, organisation, and sometimes rewriting, not just the act of correcting mistakes.

Option C, rephrase, is about changing the wording, sometimes for clarity, but it does not always imply the removal of errors and is therefore not a direct equivalent for emend.

Option D, No improvement, would keep the longer descriptive phrase, which is acceptable but not as concise or technical as using a single accurate verb.

Common Pitfalls:
Learners may confuse emend and amend because they sound similar, or they may instinctively choose edit because it is a familiar word related to writing. However, exam questions at this level expect recognition of subtle distinctions. Remember that emend and amend are near synonyms in the context of correcting texts, whereas edit is a wider process and rephrase is focused on wording change rather than correction of mistakes.

Final Answer:
The verb that best replaces remove mistakes from it in the definition of emend is amend.