Concept:
Spelling proficiency requires understanding word structures, roots, and common patterns of consonant duplication. Identifying errors involves analyzing each word against established English orthographic rules.
Step 1: Analyze options A, B, and C.
* capitulate (verb): Spelled correctly. It means to surrender or cease to resist an opponent or an unwelcome demand.
* bilk (verb): Spelled correctly. It means to cheat or defraud someone, especially out of money.
* bane (noun): Spelled correctly. It refers to a cause of great distress or annoyance.
Step 2: Identify and correct the mistake in option D.
* The word "asiduous" is spelled incorrectly.
* The correct spelling is assiduous, which requires a double 's'.
* Meaning: Showing great care, attention, and perseverance in a task or duty.