In his address to the candidates contesting the student council elections the Principal said, “If you want others to take you seriously then you must __________ on issues like gender bias and inclusivity.ˮ

In his address to the candidates, the principal emphasised the value of authenticity in leadership, especially when it comes to social issues like inclusivity and gender bias.  The blank requires a phrase meaning to act consistently with one’s stated principles—to demonstrate sincerity rather than just making promises.

"Walk the talk" (Option C) is an idiom that specifically means to back up words with actions, ie support statements with deeds. It encapsulates the principal's demand that candidates live up to the principles they support, guaranteeing that their campaign rhetoric is translated into actionable conduct.

This meaning is not conveyed by the other options: "Go around the bend" (Option B) suggests irrationality, which is completely out of context; "Rule the roost" (Option A) implies domineering control, which runs counter to the collaborative spirit of student leadership; and "Read the lines" (Option D) implies superficial engagement, the opposite of the deep commitment the Principal demands.

Thus, Option C is the only phrase that maintains the sentence’s intent and grammatical coherence, making it the correct choice here.