The correct answer is A. Exploit
Step-by-step explanation:
Although all the words presented (exploit, exploited, explore and exponent) have a similar spelling and include the prefix "ex-" each of them has a different meaning. In this way, exploit is a verb that describes to use something for profit but also as a noun it refers to a heroic or notable act; the word exploited means something or someone that has been exploited; the word explore means to travel or similar and the word exponent means someone that is a representative or similar. This means the word that means a remarkable or heroic act or deed is Exploit.