w3c markup validator ampersand (&) error

Question

Is there any workaround for the w3c validation error for an & present in urls or some other place in HTML markup?
It says:

&

Answer 1

should be:

c91588793296e2?s=50&d=http%3A%2F%.

notice the &

I know it feels wonky, but ampersands have to be encoded as html entities, which are confusingly denoted with ampersands.