A biologist identifies a mutant line of mice that lacks the cellular immune response. She suspects that a mutation in these mice affects the ability of host cells to carry out the antigen presentation step during the activation phase. What could the biologist do to test her hypothesis

Isolate antigen-presenting host cells from mice known to have an intact cellular immune response and inject these into the mutant mice to see if the normal response can be restored.

for example, no new evidence will demonstrate that the earth does not orbit around the sun (heliocentric theory), or that living things are not made of cells (cell theory), that matter is not composed of atoms, or that the surface of the earth is not divided into solid plates that have moved over geological timescales .