This patient presents with classic upper motor neuron lesion symptoms: weakness, hyperreflexia, and decreased sensation. However, the question states she "cannot tell whether her left great toe is raised or depressed" when her eyes are closed, which may make you reconsider and think there may be some proprioceptive issues they are trying to hint at. This is not the case. Especially once they mention there are no other abnormalities (i.e., no upper limb abnormalities or right sided abnormalities). If this is the case, there is no damage to the tracts at all (which are still considered UMN).
Therefore, the damage is purely motor and sensory in the left leg, which is on the medial aspect of the frontal and parietal lobes respectively. This area is supplied by the anterior cerebral artery.