Grammar improvement: choose the best replacement for the bracketed part in The Chairman appointed her (as a secretary) as she is efficient.

Introduction / Context:
This question tests knowledge of verb complement patterns in English, specifically how we express appointments to roles or positions. The sentence given is The Chairman appointed her as a secretary as she is efficient, where the phrase as a secretary is underlined for improvement. We must select the grammatically most natural way to complete the structure appointed her blank.

Given Data / Assumptions:

The main verb is appointed, and the direct object is her.
The phrase describing the new role or position is currently as a secretary.
The additional clause as she is efficient explains the reason but does not affect the pattern of appointment.

Concept / Approach:
In standard English, verbs such as appoint, elect, and make often take an object followed by an object complement that names the role without using as or an article, for example They appointed him manager or They elected her president. While some speakers do use as after appoint, exams based on formal grammar usually prefer the pattern appointed her secretary. Therefore, the best correction is to remove both as and the article a, leaving the bare noun secretary as the complement.

Step-by-Step Solution:
Step 1: Identify the grammatical pattern: subject The Chairman, verb appointed, object her, and complement describing her new role. Step 2: Recall the common structures used in formal English, such as appointed him treasurer or elected them members. Step 3: Compare these with the original phrase as a secretary and notice the unnecessary as and article. Step 4: Substitute the simple complement secretary to form The Chairman appointed her secretary as she is efficient. Step 5: Read the sentence again to ensure that it is clear, concise, and grammatically standard.

Verification / Alternative check:
We can check similar examples: The board appointed Ravi director, The committee elected Meena chairperson, and They made Raj captain of the team. All these follow the pattern object plus noun complement without as. Although casual speech sometimes includes as, many grammar references and examination standards prefer the shorter structure. Therefore, appointed her secretary is the safest and most accepted form to choose in a competitive exam setting.

Why Other Options Are Wrong:
Option A a secretary gives The Chairman appointed her a secretary, which is ungrammatical because the verb appointed already takes the direct object her, so a secretary cannot also serve as a second direct object in this form.
Option B as secretary still keeps as, which many standard references mark as unnecessary or less formal in this pattern.
Option D No improvement leaves as a secretary unchanged and does not match the preferred concise structure tested in such questions.
Option E to the post of secretary is grammatically possible but wordy and not required by the exam when a more direct pattern exists.

Common Pitfalls:
Learners often overuse as in sentences like appointed her as the leader or selected him as the representative. While not always wrong in informal usage, these forms can be marked as nonstandard in exams. To avoid confusion, remember that verbs such as appoint, elect, call, and make usually follow the pattern object plus complement without a linking preposition, especially in formal written English.

Final Answer:
The best improvement is to replace the underlined words with secretary, giving The Chairman appointed her secretary as she is efficient.