Which note is one fret lower than D# on the A string?

To determine which note is one fret lower than D# on the A string, we need to identify what note D# corresponds to on the guitar fretboard. On the A string, the note D is located two frets down from D#.

Starting from D#, if you move one fret lower, you will land on D. This is the note that is directly one fret below D#.

In the context of an A string, moving one fret down from D# leads to D, supporting the understanding of how to navigate the fretboard by knowing the musical notes and their respective positions in relation to one another.

Understanding the structure of half steps is crucial here since moving down one fret represents a half step decline in pitch. Hence, identifying that D lies one fret below D# helps reinforce the knowledge of the relationship between notes on the guitar fretboard.