Concept:
An antonym is a word that has the exact opposite meaning of another word.
• Target Word: Indolent is an adjective that describes a person who avoids activity or exertion; it is a formal synonym for being lazy or idle.
• Objective: Find a word that represents high energy, work ethic, or constant physical and mental engagement.
Step 1: {Evaluating each option against the target word.}
• active: This word describes someone who engages in energetic work or action. It stands as the direct structural opposite of being indolent.
• lazy: This is a direct synonym of indolent, not an opposite.
• dull: This means lacking interest, brightness, or sharpness, which does not match the concept of activity levels.
• brilliant: This means exceptionally clever or bright. While a lazy person can be brilliant, brilliance is not the direct antonym of physical or mental laziness.
Step 2: {Final check.}
Since "indolent" means inactive and lazy, its true grammatical opposite must be "active." The provided exam output confirms this with a green check mark next to option (1).