Final answer:
Mutations in lacP (promoter) and lacI (repressor gene) affect lac operon expression, acting respectively in a cis manner for lacP affecting only the operon on the same DNA molecule and in a trans manner for lacI affecting any lac operon in the cytoplasm.
Step-by-step explanation:
If there are mutations in each of lacP and lacI, the true statement would be that these are mutations that are, respectively, cis and trans acting on lac operon expression. LacP refers to the promoter of the lac operon, and mutations in this region would affect the binding of RNA polymerase, thereby affecting the transcription of the lac operon in a cis manner, meaning it only affects the operon on the same DNA molecule. On the other hand, LacI encodes the lactose repressor protein, which can diffuse through the cytoplasm and act on any lac operon, therefore a mutation in the lacI gene acts in a trans manner.