Final answer:
The statement given is false; mutants can actually complement each other even if the genes are involved in the same pathway, as long as they contribute differently to the pathway.
Step-by-step explanation:
The statement 'For two mutations, each occurring in separate genes, mutants can complement each other only if the genes are not involved in the same pathway' is False. Mutants can complement each other if the genes are in the same pathway, as long as they produce products that do not interact directly in the same step of the pathway. This means that each mutant could provide a functional gene product that the other is lacking, thus restoring the normal function. This is known as complementation. However, if the mutations affect different steps in the same biochemical pathway, then one mutation could potentially compensate for the other, which is a demonstration of epistasis. In this case, the functioning gene product from one mutant could cover up or cancel out the deficiency in the other, thus allowing for some normal cellular or organismal function.