<prompt> Which of the following monoclonal antibody is used for treatment of colorectal carcinoma?PembrolizumabCetuximabRituximabNatalizumab  <response>: Cetuximab - Colorectal cancer, Head and neck cancer. Rituximab - B cell NHL, CLL Natalizumab - multiple sclerosis Pembrolizumab - head and neck cancer JC virus antibody titre measurement is mandatory during treatment with Natalizumab 