Which is an advantage of producing genetically engineered crops that have pest-resistant genes?
bioaccumulation of crops over time
allows farmers to grow any crop they want
reduces the use of pesticides for certain insects
gene transfer to nontarget species

The correct answer would be "reduces the use of pesticides for certain insects".

Genetic engineered plants are those which are genetically modified by introducing a foreign gene in them. The foreign gene provides the plants with characters such as high yield, pest resistance, high shelf life et cetera.

Pest-resistance ability enables the crops or plants to resist the growth or invasions of pests.  

For example, Bt cotton is a genetically modified crop made by inserting a gene (cry gene) from bacterium Bacillus thuringiensis. This gene encodes for insecticidal toxins that make the Bt cotton resistant against butterflies and moths, cotton bollworms, beetles et cetera.

Thus, pest resistance gene reduces the dependency of farmers on pesticides.

"1. it should be, it has been for about 20 years, and it's really not much different in the end than breeding animals to have particular traits. there are always concerns about genetically engineered animals/plants affecting the environment in unexpected negative ways, but i can't think of an example where the fears didn't turn out to be baseless.  

first, as you point out, it would be a great advance in pharmacology, to be able to tailor drugs and their doses to me. the pros involve better medical treatment. the cons involve privacy issues like insurance companies denying coverage to people with genetic risk factors. looking at dna markers wouldn't affect the frequency of genetic diseases, but it would allow detection of them earlier. and ok, actually i suppose that if people used this information to avoid having children with genetic diseases, some might decrease in frequency."