As noted by other educators, this is a subjective question. There could arguably be more than one correct answer. If the question refers to an assigned class reading from a textbook or article, then the answer should match the opinion of that author.

Otherwise, I would argue for choice B. The 1960s counterculture gave birth to rock music, and bands and songs from that era are still popular and influential today. It also popularized new types of art and literature. But in my opinion, the era had the most lasting impact on social attitudes. The 60s was a decade of protest and change. Major civil rights laws were passed, women began entering the workforce, and the Vietnam War galvanized protesters. The casual use of marijuana helped pave the way for its legalization today in several US states. Likewise, casual use of stronger drugs—particularly LSD—has led them to be outlawed.

The Graduate, a 1967 film, captures the angst of a young college graduate who ostensibly has a solid job and promising career ahead of him. But that seems hollow to him, as it must have to thousands of other young people at the time, and he rejects that path while struggling to find meaning in his new adult life. It's a good representation of the generational divide between young people in the 60s and their parents.

The 1960s counterculture movement had the most lasting impact on the attitudes toward lifestyle and social behavior, art, and music. The 1960s saw many changes in our society, and these changes were significant.

As a result of the counterculture, new forms of art and music developed. Rock became very popular and artists such as Bob Dylan, Janis Joplin, and Jimi Hendrix became famous. The Beatles were also a popular music group. Pop art developed during this time, and Andy Warhol became famous.

Different lifestyles became evident as a result of the counterculture. People began to protest against issues that they perceived as unfair. People were worried about nuclear weapons, the Vietnam War, and the perceived dishonesty of the government. People were no longer content to accept events that they believed were wrong. They began to protest about them. People wore flashier clothing and were less willing to conform to the norms of society. The concept of individuality was stressed. People wore their hair longer. Drug use also increased.

These changes in social behavior, lifestyle, art, and music were major changes. In some ways, the counterculture made long lasting changes in our culture and in our society.

Therefore, I would say answer B is correct.

This is not a question that can really have an obectively correct answer.  I would suggest that you look for what your textbook says is the correct answer.  The impacts of the counterculture can certainly be debated and at least two of these answers could be seen as correct.

I would argue that the best answer is B.  I would argue that the counterculture had a greater impact on American society than on the political process.  I would argue that the counterculture helped make Americans rethink things like the role of women and minorities in society.  It helped bring about the "sexual revolution" that has impacted US culture.  These changes, I would argue, are greater than its impact on the political system.