Final answer:
Macbeth regrets becoming king as he sees the crown as 'fruitless' and the scepter as 'barren', indicating he believes his power will yield no legacy.
Step-by-step explanation:
When Macbeth says 'Upon my head they placed a fruitless crown / And put a barren scepter in my gripe,' he is expressing his feelings of frustration and futility. This statement implies that in Macbeth's perspective, the crown brings him no satisfaction or heirs, and hence is 'fruitless'. He regrets becoming king because he understands that he has no legacy to leave behind, and the power he holds ('barren scepter') will not yield any lasting progeny or benefits.
The correct answer to the student's question is: He regrets becoming king (b). The crown and scepter are symbols of his kingship and power, but they bring him no fulfillment. Macbeth is aware that despite having the titles and outward signs of authority, they will not grant him the legacy he desires.