Final answer:
Low blood pressure is NOT a usual side effect of adrenergics; rather, adrenergics typically cause an increase in blood pressure.
Step-by-step explanation:
The usual side effects of adrenergics such as adrenaline or norepinephrine include nervousness, increased blood sugar, and a fast heart rate. These effects are in line with the fight-or-flight response, which prepares the body for rapid action in stressful situations. Adrenergic drugs mimic the action of adrenaline and typically cause an elevation in blood pressure, not a reduction. Therefore, low blood pressure (hypotension) is not a usual side effect of adrenergics, making option 'b' the correct answer to the question.