For this journey you are miniaturized and injected into the interior of the largest bone of your host body, the

the largest bone is the femur.

The femur is the thigh bone, the proximal segment of the lower limb. It is the longest, the largest (by its volume), and the most solid (when taking into account its resistance to mechanical stress, contraction of muscles ...) bone of the human body.

The femur consists of a central part, the body or diaphysis and two extremities, the epiphyses.

i think that the best answer would be c.

tell me if im wrong : )