Final answer:
George Martin was pivotal in shaping Lennon & McCartney's songwriting by offering musical arrangements, production enhancements, and creative suggestions that significantly impacted The Beatles' music and popular music at large.
Step-by-step explanation:
George Martin played a crucial role in the development of Lennon & McCartney as songwriters during his time as The Beatles' producer. Often referred to as the "Fifth Beatle," Martin's classical music background and production skills were instrumental in shaping the band's sound.
He provided sophisticated musical arrangements, suggested structural changes to their songs, and incorporated unconventional instruments and recording techniques that helped transform Lennon & McCartney's raw ideas into polished hits. Martin's contributions greatly enhanced the complexity and appeal of The Beatles' music, which ultimately had a profound impact on popular music.