What is the size of the angle representing spaghetti?

$$360^\circ - 260^\circ = 100^\circ$$

The angle representing spaghetti is $100^\circ$.

The correct option is (a).

$$\boxed{\text{a) } 100}$$

$$\frac{1}{15} \times 450 = 30$$

The number of pupils who ate rice is 30.

The correct option is (d).

$$\boxed{\text{d) } 30}$$

The correct option is (c).

$$\boxed{\text{c) pie-chart}}$$