What causes a solution to a rational equation to be an extraneous solution?
a. when there is more than one solution, one of the solutions is extraneous.
b. if a solution results in zero when substituted into the denominator of the equation, the solution is extraneous.
c. if a solution results in a negative number when substituted into the denominator of the equation, the solution is extraneous.
d. when a solution is a fraction, the solution is extraneous.