Final answer:
The Beatles returned to London from the US on March 21, 1964, encompassing the essence of suburban youth culture during the mid-1960s and influencing events like Woodstock.
Step-by-step explanation:
The Beatles returned from the US to London on March 21, 1964. The date you are looking for is option B) March 21, 1964. This period marked an important era in music and cultural history, as The Beatles were pivotal in embodying the suburban youth culture of the mid-1960s. Their influence extended beyond music to the wider culture, including the Woodstock festival in 1969, which was one of the most iconic events of the era.