What is the note on the 8th fret of the 3rd string?

The note on the 8th fret of the 3rd string, which is the G string on a standard-tuned guitar, is the note D. The 3rd string, when played open, is tuned to G. As you move up the fretboard, you are essentially raising the pitch of the string.

Starting from G: the notes progress as follows: G (open), G# (1st fret), A (2nd fret), A# (3rd fret), B (4th fret), C (5th fret), C# (6th fret), D (7th fret), and finally, D# at the 8th fret. Hence, the note at the 8th fret is indeed D, which corresponds to the choice that indicates this note.

Understanding this movement along the fretboard is crucial for mastering the guitar, as it allows you to identify notes quickly and enhances your ability to jam in various musical contexts.