A Student Determined the Equilibrium Concentration in the Following Equation $\frac { x ^ { 2 } } { ( 0.05 - x ) }$

A student determined the equilibrium concentration in the following equation by neglecting the x term in the denominator. Was she justified or not in this approximation and why?
K = 4.0 *10^-2 = $\frac { x ^ { 2 } } { ( 0.05 - x ) }$

A) Yes, the concentration is much greater than K, so the x can be ignored.
B) Yes, the value of x determined in this way is less than 0.05, so it can be ignored.
C) No, the value of x determined in this way significantly reduces the denominator.
D) No, the value of x can never be ignored in solving an algebra problem.
E) No, the value of K is much less than 1, so x cannot be ignored.