Final answer:
Generation X includes individuals born between the early 1960s and the 1980s, with the correct answer being the 1970s and 1980s (option b).
Step-by-step explanation:
Generation X refers to the cohort born between the early 1960s and the 1980s. Therefore, the correct answer to which decades Generation X falls under is b) 1970s and 1980s. While there is some variation in the exact years different sources use to define Generation X, a commonly accepted range is from the early '60s to the early '80s. This means that individuals born in the 1960s and 1970s would predominantly be a part of Generation X, with those born in the latter end of this range entering early adulthood in the 1980s.