The maximum length of the char columns is . . . . . . . .

Answer: Option A

This question is asking about the maximum size of a CHAR column in MySQL. A CHAR column stores fixed-length strings, meaning each value in the column takes up the same amount of space, even if it's shorter than the maximum length.
Let's break down the options:
Option A: 255 bytes - This is the correct answer. A CHAR column can hold a maximum of 255 characters.
Option B: 65,535 bytes - This is the maximum length for a VARCHAR column, which stores variable-length strings.
Option C: 256 bytes - This is incorrect.
Option D: None of the mentioned - This is also incorrect since Option A is correct.
Therefore, the correct answer is Option A: 255 bytes.