Mutations may have an effect on the expression of the lac operon and the trp operon. Would the following mutations have a cis- or trans-effect on the expression of the protein-encoding genes in the operon?
A. A mutation in the operator site that prevents the lac repressor from binding to it
B. A mutation in the lad gene that prevents the lac repressor from binding to DNA
C. A mutation in trpL that prevents attenuation