In the following question, out of the four alternatives, select the one-word substitute that best expresses the meaning of the given phrase: The faculty or power of using one's will.

Introduction / Context:
This one word substitution question deals with a psychological and philosophical term that describes the mental power behind making choices. The phrase “the faculty or power of using one's will” refers to the inner ability to decide and act intentionally. You must pick the technical word that captures this idea accurately.

Given Data / Assumptions:

• Phrase: The faculty or power of using one's will.
• Options: Antagonism, Aversion, Rejection, Volition.
• We are talking about willpower and choosing, not about feelings of dislike or conflict.
• The desired word is often used in psychology, law and philosophy.

Concept / Approach:
Volition is the faculty or power of using one's will. It refers to the act of making a conscious choice or decision. Antagonism means active hostility or opposition, aversion means strong dislike, and rejection means refusal to accept something. All three are about negative attitudes, not about the neutral or positive power to choose. Volition alone matches the phrase by directly referring to deliberate, willing action.

Step-by-Step Solution:
Identify the key elements in the phrase: “faculty or power” and “using one's will”.Recall that the technical term for willpower or the act of willing is volition.Check Antagonism: this describes hostility or opposition to someone or something.Check Aversion: this means strong dislike or unwillingness towards something.Check Rejection: this is the act of refusing to accept or agree.Only Volition refers to the internal power to choose and act according to one's will.

Verification / Alternative check:
Use the word volition in an example: “He signed the contract of his own volition,” meaning he signed it by his own free will, without force. This exactly reflects “use of one's will.” If we try to substitute antagonism, aversion or rejection, the sentence becomes nonsensical: “of his own antagonism” or “of his own rejection” do not express the idea of freely choosing. This confirms that volition is the correct one word substitute.

Why Other Options Are Wrong:
Antagonism focuses on conflict and animosity, not on choice or will. Aversion refers to a strong feeling of dislike or avoidance, which is not the same as the power to choose. Rejection is an outward act of refusing, not the inner faculty that allows a person to make any decision, whether yes or no. The question is concerned with the capability of willing, not with particular emotional attitudes, so these options must be eliminated.

Common Pitfalls:
Because aversion and rejection are common words, students sometimes select them out of familiarity. However, one word substitution questions frequently use slightly technical vocabulary. When you see references to will, choice or free decision, remember volition as the precise term. Building mental links like “voluntary, volunteer, volition” (all connected to will) helps you recall this word accurately in competitive exams.

Final Answer:
The one word substitute for “the faculty or power of using one's will” is Volition.