Correct Answer: Skill

Solution : The correct choice is the third option.

Ability refers to a capacity or capability, particularly in the context of having the same skill as the speaker. Skill is a synonym for ability and is often used to describe a learned or acquired capacity to perform tasks effectively and with expertise. Both words convey the idea of possessing the necessary qualities to perform a particular action or task.

The meanings of the other options are as follows:

• Feature: It denotes a distinctive attribute or aspect of something.
• Inefficacy: It means failure to produce the desired effect.
• Flexibility: It denotes the ability to be easily modified.