In this one word substitution question, choose the correct English word that is used for "a person who is able to use both hands with equal skill".

Introduction / Context:
One word substitution questions aim to test your precise vocabulary. You are given an explanatory phrase and asked to pick the single word that carries the same meaning. In this case, the description is "one who is able to use both hands". This is a familiar concept in English, especially in sports, medicine, and everyday description of people's abilities.

Given Data / Assumptions:

• The phrase describes a person who can use both hands equally well.
• Four possible single word substitutes are provided.
• You need to identify the standard English term for such a person.
• The answer should be a widely accepted dictionary word.

Concept / Approach:
To solve one word substitution questions, focus on the key idea and then recall the technical or widely used term. Here the key idea is equal ability in both hands. The English word for this is "ambidextrous". It comes from Latin roots meaning "both right" or "both favourable hands", indicating that the person can perform tasks efficiently with either hand.

Step-by-Step Solution:
Step 1: Identify the core idea: equal use of both right and left hands.Step 2: Think of contexts where this idea is used, such as cricket, tennis, or drawing, where some people can bat or write with both hands.Step 3: Recall vocabulary from reading: "ambidextrous" is commonly used to describe such people.Step 4: Compare each option with the idea. Only one option mentions both hands implicitly through its root meaning.Step 5: Confirm that "Ambidextrous" is the correct and exact word for someone who can use both hands equally well.

Verification / Alternative check:
To check your answer, place the candidate word into a sentence: "She is ambidextrous and can write with both her right and left hands." This sentence is meaningful and correct. If you substitute other options, such as "sinister" or "amateur", the sentence becomes awkward or completely wrong, showing that they do not match the description.

Why Other Options Are Wrong:
Option A, "Sinister", originally meant "left" in Latin but in modern English it has the sense of something evil or threatening. It does not mean "using both hands". Option C, "Ambivalent", refers to having mixed or contradictory feelings about something, not to physical ability with hands. Option D, "Amateur", simply refers to someone who does an activity for pleasure rather than as a profession. None of these options express equal skill with both hands.

Common Pitfalls:
Candidates sometimes confuse "ambidextrous" with "ambivalent" because both start with "ambi". However, "ambi" in "ambivalent" relates to two different feelings, while in "ambidextrous" it refers to both hands. Always connect the word not just to its sound, but to the meaning you have learned from examples and context in your reading.

Final Answer:
The correct answer is Ambidextrous, the standard English word used for a person who can use both hands with equal skill and efficiency.