Which is a way that your body builds resistance to certain pathogens? a. by exposure to pathogens, or having a certain disease b. by vaccination c. by producing b and t cells when your body encounters an antigen d. all of the above?

The answer is d (All of the Above). While vaccination is a way of introducing attenuated pathogens into the body to invoke an immune response and memory, ocassionaly, an infection of disease can also invoke immune response and memory after healing. This immune memory is mainly through memory T and B cells.

Its either a) or b),wind and water erosion gradually widen the canyon