The question is examining the understanding of词汇 related to ability. The correct answer is 'B. Inability' because it refers to the lack of ability to do something. Option A is incorrect because 'capability' refers to the capacity to do something, not the lack of it. Option C is incorrect because 'ability' refers to the skill or power to do something, which is the opposite of the term being asked for. Option D is incorrect because 'possibility' refers to the potential that something could happen, not the ability to do it.