Peter from Norway dreams of attending college in the U.S. As Peter has never visited the U.S.,

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Peter from Norway dreams of attending college in the U.S. As Peter has never visited the U.S., he plans to visit a few schools before deciding which schools to apply. He only intends to stay for a couple of months over the summer, so Peter was told he did not need a visa to enter the U.S. On June 13, 2018, Peter entered the U.S. using his Norwegian passport. Halfway through his trip, Peter meets Mark, a U.S. citizen grad student at MIT and the two fall in love. Unwilling to be separated, the couple decides Peter should move in with Mark and apply to MIT. On September 1, 2018, Peter is accepted to his academic program for the Spring 2019 semester. Amongst documents requested by MIT is proof of Peter's eligibility to attend school in the U.S. What type of visa does Peter need?Why ? Explain