Correct Answer: Considerable

Solution : The correct answer is the third option.

The word "considerable" means large or significant in size, amount, or degree. In the context of the given word "major," "considerable" is a synonym, as both convey the idea of being important or significant.

The meanings of the other options are as follows:

• Diligent means showing care and effort in one's work.
• Shallow means lacking depth, both physically and metaphorically.
• Creviced refers to having crevices or cracks.

Therefore, the correct answer is considerable.