Final answer:
Eddie Van Halen is credited with popularizing the use of the synthesizer in heavy metal, specifically with the song 'Jump' by his band Van Halen.
Step-by-step explanation:
The question asks about a musician who was the first to introduce or reintroduce the synthesizer into heavy metal. The choices provided are George Lynch, Pete Townsend, Eddie Van Halen, and David Lee Roth.
It's important to note that while some of these musicians have used synthesizers, Eddie Van Halen is recognized for his innovative guitar work and use of synthesizers in the heavy metal genre, notably in the album '1984' by Van Halen, featuring the iconic song 'Jump' which heavily features the synthesizer.
However, the actual reintroduction of synthesizers into heavy metal is a subject of debate among fans and historians, as other bands and artists may have experimented with the instrument at various points.