Which note corresponds to the 2nd fret of the D (4th) string?

To determine the note that corresponds to the 2nd fret of the D (4th) string, it's important to understand the standard tuning of the guitar. The D string is tuned to the note D in open position.

When you press down on the 2nd fret of the D string, you raise the pitch of the open D note by two half steps (also known as semitones). The sequence of notes moving up from D by one half step each time is as follows: D (open), D# (1st fret), E (2nd fret). Therefore, the note at the 2nd fret of the D string is E.

This method of counting half steps is essential for every string and fret on the guitar, and recognizing the pattern allows you to easily find notes across the fretboard. Consequently, the correct answer of E reflects this understanding of how fretted notes relate to their open string equivalents and the chromatic scale.