You Are Interested in Cell-Size Regulation and Discover That Signaling

You are interested in cell-size regulation and discover that signaling through a GPCR called ERC1 is important in controlling cell size in embryonic rat cells.The G protein downstream of ERC1 activates adenylyl cyclase, which ultimately leads to the activation of PKA.You discover that cells that lack ERC1 are 15% smaller than normal cells, while cells that express a mutant, constitutively activated version of PKA are 15% larger than normal cells.Given these results, which of the following treatments to embryonic rat cells should lead to smaller cells?

A) addition of a drug that causes cyclic AMP phosphodiesterase to be hyperactive
B) addition of a drug that prevents GTP hydrolysis by Gα
C) addition of a drug that activates adenylyl cyclase
D) addition of a drug that mimics the ligand of ERC1