You want to study the effect of a mutation in your favorite gene in a cell. You do not plan to purify the gene product, just look at the mutation in vivo. What of the following would be a the best choice of a cloning vector?

a. a vector that overexpresses YFG
b. a vector that allows you to fuse YFG with a 6xHIS tag
c. a single copy vector ( I think this is the right answer)
d. a multicopy vector