Which of the following words is closest in meaning to “Acumen”?

Acumen means sharp judgement and keen insight; cleverness.

• Correct answer - cleverness: it has the same meaning as Acumen.
• obtuseness: slowness of understanding - wrong, it does not mean the same as Acumen.
• adamant: refusing to change one's mind - wrong, it does not mean the same as Acumen.
• dullness: lack of sharpness or interest - wrong, it does not mean the same as Acumen.