Evaluate $\underset{x}{lim}\frac{1-x}{2x},\underset{x-}{lim}\frac{1-x}{x^2},$ and $\underset{x}{lim}\frac{1-x^2}{2x}.$

Select the correct choice and, if necessary, fill in the answer box to complete your choice.

A$.\underset{x}{lim}\frac{1-x}{2x}=-\frac{1}{2}($Simplify your answer.$)$

B$.$ The limit does not exist and is neither $-$ nor $.$

Select the correct choice and, If necessary, fill in the answer box to complete your choice.

A$.\underset{x-}{lim}\frac{1-x}{x^2}=0($Simplify your answer.$)$

B$.$ The limit does not exist and is neither $-$ nor $.$

Select the correct choice and, if necessary, fill in the and $\frac{1}{2}r$ box to complete your choice.

A$.\underset{x}{lim}\frac{1-x^2}{2x}=0($Simplify your answer.$)$

B$.$ The limit does not exist and is neither $-$ nor $.$