What is the difference between "major" and "minor" chords?

The distinction between major and minor chords primarily lies in their tonal quality, which is best summarized in the correct choice. Major chords are characterized by a bright, happy sound, often evoking a sense of joy and optimism. This brightness comes from the specific intervals that make up the chord, particularly the major third interval between the root note and the third note. In contrast, minor chords produce a darker, more somber tone, largely due to the minor third interval that gives the chord its signature sound.

The other options touch on aspects that do not accurately describe the fundamental differences between major and minor chords. While it's true that different chords can pose various levels of difficulty depending on the context and the musician's skill level, the ease of playing is not a defining characteristic of the chords themselves. Additionally, both major and minor chords can utilize sharps and flats, depending on the key in which they are played. Finally, the method of playing a chord (using one hand or two) is not inherently tied to whether the chord is major or minor, as both can be played in a variety of ways depending on the arrangement and the instrument.