a. a group

b. a period

c. an individual element

d. none of the above

I think it’s c because there all individual elements, not in a group

That would be kinetic energy

The radiation of the fire causes the saucepan to heat up. the conduction of the saucepan then to distribute the heat over the saucepan and to give heat to the water. the convection of the water distributing the heat within the water, till all the water is boiling