Which ocean is the smallest and shallowest of the world's five major oceans?

The correct answer is A.

The Arctic Ocean is recognized as the smallest and shallowest of the world's five major oceans. It is located around the North Pole.

• B. The Southern Ocean is the fourth largest.
• C. The Indian Ocean is the third largest.
• D. The Atlantic Ocean is the second largest.

The final answer is $\boxed{\text{A. Arctic Ocean}}$