Bullock-cart is pulled by bulls.

Explanation:
A bullock-cart is a traditional form of transportation still used in many parts of rural India. It consists of a two-wheeled cart or wagon drawn by a pair of oxen or bulls. The bulls are trained to walk in tandem and pull the cart forward. They are usually guided by a person called a driver or a bullock-cart driver who sits on the cart and controls the direction and speed of the animals.

The use of bullock-carts for transportation has been a part of Indian culture for centuries. The bulls are strong, sturdy and can pull heavy loads over long distances. They are also well-suited to working in rural areas where roads may be narrow and uneven.

In addition to transportation, bullock-carts are also used for agricultural purposes like plowing fields and carrying crops. They are still a common sight in rural India, especially in areas where modern transportation is not easily available.

In conclusion, bullock-carts are pulled by bulls, and this traditional form of transportation continues to be an important part of Indian culture and rural life.

Answer D is correct