The graph illustrates the primary and secondary immune system responses to antigens. What are responses X and Y?
- AX: primary response; Y: secondary response caused by cloning of B-lymphocytes formed during the primary response
- BX: primary response; Y: secondary response caused by cloning of T-lymphocytes formed during the primary response
- CX: secondary response caused by cloning of B-lymphocytes formed during the primary response; Y: primary response
- DX: secondary response caused by cloning of T-lymphocytes formed during the primary response; Y: primary response