Correct Answer & Explanation
Option A
• 'Foe' means an enemy or opponent in a contest, conflict, or war.
• The word 'Adversary' means one's opponent in a contest, conflict, or dispute, making it the exact synonym of 'foe'.
• Options B, C, and D are incorrect because 'Ally' and 'Comrade' mean friends or companions, while 'Pioneer' refers to an early developer or explorer.