McCandless sees his time in college as A. a time of youthful naivete that he regretted B. intense preparation for his Alaskan odyssey C. an absurd and onerous duty D. the catalyst for his new way of viewing the material world E. an exploration of the truth of mankind's purpose

The answer is C. an absurd and onerous duty. He described the previous four years in college as a preparation for graduation which is an absurd onerous duty for him. After graduation, he began his adventure and he felt free from the suffocating world of his parents and materialism.