Mutations Causing Deficiencies in CD40L Expression Lead to an Inability

Mutations causing deficiencies in CD40L expression lead to an inability of helper T cells to:

A) kill tumor cells, resulting in an increased risk of cancer.
B) activate macrophages, resulting in an inability to clear extracellular pathogens.
C) migrate to the site of an infection by chemotaxis, resulting in a slowed response.
D) promote class-switching, resulting in high IgM and low IgA and IgG concentrations.