Define "proliferate."

Proliferate is a mechanic in Magic: The Gathering that specifically involves adding counters to permanents or players that already have a counter. The correct definition of proliferate states that you can choose any number of permanents and/or players that have a counter on them and give each of those exactly one additional counter of a kind they already have. This means that proliferating is about increasing the number of counters on specific targets that already possess them, based on the counters they currently have.

This concept allows for strategic manipulation of counters, especially in decks that rely on counters for various effects, such as poison counters or charge counters on artifacts. The focus is on enhancing existing counters rather than introducing new ones or affecting permanents and players that do not currently have counters.

The other options do not accurately capture the mechanics of proliferate. For instance, destroying a permanent does not relate to adding counters at all, while adding counters to all permanents disregards the requirement that those permanents must already have counters to begin with. Removing a counter does not pertain to proliferate, as it does not involve the addition of counters but rather the subtraction. Understanding the nuances of proliferate is crucial for properly utilizing it within gameplay.