Final answer:
The error in voice leading between chords 2 and 3 would be identified as parallel fifths. It is important to avoid parallel fifths in traditional four-part harmony as it can result in a lack of independence and harmonic richness.
Step-by-step explanation:
The error in voice leading between chords 2 and 3 would be identified as parallel fifths. Voice leading refers to the way individual voices move from one chord to another in a musical composition. Parallel fifths occur when two voices move in parallel motion, staying a fifth apart, which can create a dissonant and undesirable sound.
An example of parallel fifths can be seen in Figure 7.1.1, mentioned in the question, where the movement from chord 2 to chord 3 involves the voices moving in parallel fifths (C and G in the bass voice, and A and E in the tenor voice).
It is important to avoid parallel fifths in traditional four-part harmony as it can result in a lack of independence and harmonic richness.