Final answer:
The skin condition with symmetrically arranged, brightly erythematous macules and papules is most likely to be an exanthematous (morbiliform) drug eruption, which is a systemic reaction to medication.
Step-by-step explanation:
The skin condition described as symmetrically arranged, brightly erythematous macules and papules, which are discrete in some areas and confluent in others, is most consistent with e) exanthematous (morbiliform) drug eruption. This type of reaction typically occurs as a symmetrical rash that can be widespread and involves red, often itchy, spots that can coalesce to form larger areas of redness. It's a cutaneous adverse drug reaction and can happen systemically, manifesting in lesions on the skin. Exanthematous drug eruptions generally occur within the first two weeks after a person starts a new medication, and they resolve upon withdrawal of the offending drug.