Objective: How to melt marshmallows in microwave

Which of the following solutions is more sound in terms of naive physics reasoning?

Choices: a). Place the marshmallows in a large microwave-safe bowl. Turn on the microwave, set to high, for 3 seconds. Take the bowl out of the microwave and stir the marshmallows.. b). Place the marshmallows in a large microwave-safe bowl. Turn on the microwave, set to high, for 30 seconds. Take the bowl out of the microwave and stir the marshmallows..
b).