A 58-Year-Old Woman Complains of Left Hand Weakness That She

A 58-year-old woman complains of left hand weakness that she noticed while planting flowers in her garden. Neurological examination indicates weak wrist and finger flexion and extension. She also has weakness when abducting, adducting, and opposing her thumb. All other motor and sensory tests are normal. The combined deficits in this patient can most accurately be attributed to a lesion in which of the following?

A) Left precentral gyrus
B) Left postcentral gyrus
C) Right postcentral gyrus
D) Right precentral gyrus
E) Superior frontal gyrus