52. Mouse mutations can affect an animal's appetite and eating habits. The ob gene produces a satiety factor (the hormoneleptin). The db gene product is required to respond to the satiety factor (the leptin receptor). Most obese humans producenormal or increased levels of leptin without satiety. Which might provide an answer to at least some human obesity if ameans to do so is found?
(A) overexpression of the leptin receptor gene
(B) activation of receptors for leptin
(C) supplementary leptin
(D) inactivation of leptin
(E) mutation of the leptin receptor gene