Correct answer - A (Elephants have few offspring, so they need to protect them from predators.)
Why? - The herd is led by the oldest and often largest female in the herd, called a matriarch. They live in herds so that the young elephants stay safe from predators.
The thermal energy can be defined as the type of kinetic energy which is generated due to the motions of the particles. This motion generates a temperature which can be measured easily. The type of thermal energy which flows from one substance to another when the temperature of the two substances is different is known as heat.
Hence, the blank can be filled with 'heat'.