You will be given a definition of a task first, then some input of the task.
In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.

genes coding for these molecules are purposefully mutated in a process called somatic hypermutation, and they sometimes undergo isotype switching. In a process discovered by Susumu Tonegawa, they are assembled by random selection of variable region, diversity, and joining segments, called V(D)J recombination. Both the nonspecific and specific type of these molecules are used in (*) ELISA. They enhance phagocytosis in a process called opsonization, and activate the binding of proteins C1 through C9 in the complement cascade. They fall into five major classes: G, A, M, D, and E. For 10 points, identify these bivalent Y-shaped proteins consisting of two light and two heavy chains, which recognize the epitopes of specific pathogens.
Output:
Science