SUMMIT

The word “summit” typically refers to the highest point or peak. Therefore, the word that is opposite in meaning to “summit” would be:Option C) base

“Base” refers to the lowest part or edge of something, especially the part on which it rests or is supported, which is the opposite of the summit.

The other options do not fit in this context.

Option A: “Zenith” is a term that also refers to the highest point, similar to “summit”.

Option B: “Acme” is another term for the peak or highest point.

Option D: “Submerged” refers to being below the surface of the water, but it doesn’t necessarily imply the opposite of a summit in the context of a peak or high point.

Therefore, “base” is the most appropriate choice here as it is opposite in meaning to “summit”.