Which of the following shows the extraneous solution to the logarithmic equation?

log Subscript 4 Baseline (x) + log Subscript 4 Baseline (x minus 3) = log Subscript 4 Baseline (negative 7 x + 21)
x = negative 7
x = negative 3
x = 3 and x = negative 7
x = 7 and x = negative 3