What DNA sequences control when and where the gene is turned on ?

One of the reasons that stars are so large is because

Imagine a self-reactive t cell that has not undergone clonal deletion in the thymus (that is to say, it has escaped central tolerance). if it encounters self antigen in the absence of an infection or inflammation, what will happen to this self-reactive t cell? (select two answers) (a) the t cell undergoes clonal expansion. (b) the t cell gains effector functions. (c) the t cell undergoes apoptosis. (d) the t cell becomes activated. (e) the t cell becomes anergic.

Compare the shapes of the bones of the human skull with the shapes of the bones of the human leg. how do the shapes differ? why are the shapes important?