Post MySQL 6.0, utf8 was . . . . . . . .

Answer: Option B

This question asks about the size of the utf8 character set in MySQL versions after 6.0.

UTF-8 is a way to represent characters from different languages using a single character set. The size of characters in UTF-8 can vary.

Before MySQL 6.0, the utf8 character set used 3 bytes per character (Option A).

But in later versions, MySQL changed how it handles utf8. It introduced a new character set called utf8mb4 which can represent a wider range of characters, including emojis.

utf8mb4 uses 4 bytes per character (Option B).

The other options (C, D) are not the correct sizes.

So the answer is Option B: 4 bytes.