Explanation:

- Earth's crust is predominantly composed of eight elements.

- These elements make up about 98% of the crust.

- Option:1, Carbon - Carbon is not major in the Earth's crust, constituting only a small part compared to other elements. Therefore, it does not figure among the eight major elements.

- Option:2, Silicon - Silicon is the second most abundant element in the Earth's crust.

- Option:3, Calcium - Calcium is a major component, crucial in various minerals.

- Option:4, Oxygen - Oxygen is the most abundant element in the Earth's crust.

The correct answer is:

Option:1, Carbon