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: "She has an ability for Mathematics."

Introduction / Context:
This sentence improvement question focuses on choosing the most appropriate noun to express natural talent or suitability for a subject. The sentence "She has an ability for Mathematics" is understandable but not the most idiomatic expression in standard English. You must select the word that native speakers commonly use to describe natural talent for subjects like Mathematics, music, or languages.

Given Data / Assumptions:

- Original sentence: "She has an ability for Mathematics." - Underlined phrase: "an ability for". - Options: "attitude", "aptitude", "altitude", "No improvement". - The intended meaning is that she is naturally good at Mathematics.

Concept / Approach:
The noun "aptitude" refers to a natural ability or talent for learning something, especially a subject or skill. We regularly use the phrase "aptitude for Mathematics" to describe someone who easily understands and performs well in that subject. While "ability" is not wrong as a general word, the set expression "an aptitude for Mathematics" is more precise and is the usage exam setters expect. The other options either refer to different concepts or are unrelated.

Step-by-Step Solution:
Step 1: Clarify the intended meaning: the sentence wants to say that she is naturally good at Mathematics, not just that she occasionally does well. Step 2: Recall the word "aptitude", which means natural talent or capacity for learning, as in "aptitude for languages" or "aptitude test". Step 3: Replace the underlined part with "an aptitude for": "She has an aptitude for Mathematics." This sounds formal, precise, and idiomatic. Step 4: Examine "attitude". This refers to a person's feelings or mindset, not their talent. "Attitude for Mathematics" would incorrectly shift the focus to her feelings rather than her ability. Step 5: Examine "altitude". This word refers to height above sea level and is completely irrelevant in this context. Step 6: Consider "No improvement". While "an ability for Mathematics" is understandable, exam patterns and standard collocations strongly favour "aptitude for Mathematics". Therefore, "aptitude" is the best improvement.

Verification / Alternative check:
Compare similar expressions: "He has a natural aptitude for chess" or "Students with an aptitude for science". In each case, "aptitude" emphasises natural talent. If we say "He has an ability for chess", it sounds less natural, and we would more likely say "He has the ability to play chess well". The phrase "ability for" is not as fixed or idiomatic as "aptitude for", confirming that the latter is preferred.

Why Other Options Are Wrong:
"Attitude" relates to a person's way of thinking or feeling, for example "a positive attitude", and does not directly describe talent. "Altitude" has a geographical and physical meaning about height and has nothing to do with academic skill. "No improvement" would leave an acceptable but weaker phrase in place instead of upgrading to the precise and common collocation "aptitude for Mathematics".

Common Pitfalls:
Because "ability" and "aptitude" are both associated with skill, many learners confuse them. A good rule is that "ability" is a general term, while "aptitude" is used especially for natural talent, often measured in "aptitude tests". Additionally, "attitude" is frequently misused by people who see it in similar contexts. Remember that "attitude" is about how someone feels or behaves, not about how skilful they are.

Final Answer:
aptitude is the correct improvement, giving the sentence "She has an aptitude for Mathematics."