The original castles were first made from earth and timber because—

The correct option is it takes a lot more time and energy to build a stone castle.

Explanation:

Early castle builders (such as those constructing motte-and-bailey castles) relied heavily on earth and timber because these materials were readily available and allowed for rapid construction.

Building with stone required quarrying, transporting heavy rock, and skilled masonry, which demanded significantly more time, labor, and financial resources. Therefore, earth and timber were chosen primarily because building a stone castle took far more time and energy.