What does it mean to win a clash?

Winning a clash specifically refers to the condition set forth in the game mechanic introduced in certain Magic: The Gathering cards. In a clash, each player reveals the top card of their library, and the winner is determined by the converted mana cost (CMC) of the revealed cards. The player who reveals a card with a higher converted mana cost than all other revealed cards wins the clash.

This means that if one player reveals a card with a CMC greater than any other card revealed during that clash, they are the victor of that clash. Winning a clash can lead to various beneficial effects depending on the context of the ability being used.

The other options relate to different aspects of gameplay, such as card advantage and hand size, but they do not pertain to the specific mechanics of winning a clash. Thus, option B accurately describes the condition for winning a clash in Magic: The Gathering.