What is the major key that contains 6 sharps or 6 flats?

The major key that contains 6 sharps is F sharp Major. In music theory, a key signature with 6 sharps corresponds to F sharp Major.

The reasoning behind this is tied to the arrangement of sharps in a key signature. For F sharp Major, the sharps are F#, C#, G#, D#, A#, and E#. This specific configuration signifies that the key is centered around F sharp, making it the correct answer.

In contrast, the other options refer to keys with different numbers of sharps or flats. For example, C sharp Major has 7 sharps, while D flat Major has 5 flats. A flat Major contains 4 flats, so neither of these can be categorized as having 6 sharps or 6 flats. Understanding the structure of key signatures is crucial for identifying major keys accurately.