Which is an essential feature of a while loop having the following form? while $($LoopExpression$)\{$ LoopBody $\}$

a$.$ The LoopExpression should not be affected by the LoopBody

b$.$ The LoopBody should get user input

c$.$ The LoopExpression should be affected by the LoopBody

d$.$ The LoopBody should update at least two variables