Task: Text Categorization
Input (English): Question: In the process of maturation of the affinity of the B lymphocytes in the germinal centers, they act as accessory cells: 
 Options:  <0> Macrophages <1> Th1 lymphocytes. <2> Mastocytes <3> Follicular dendritic cells. <4> Langerhans cells.
Output (English): biology