Which of the following statements is correct regarding heat?

$1$. Heat is a form of energy.

$2$. A mirror can reflect heat.

$3$. Heat is electromagnetic radiation.

$4$. Heat cannot pass through the vacuum.

Select the correct answer using the codes given below:

Two bodies A and B are of the same mass and the same amount of heat is given to both of them. If the temperature of A increases more than that of B because of heat addition, then _____.

Consider the following statements:

1. A heat engine is a device which converts heat energy into mechanical energy.

2. A heat engine essentially consists of a source of heat at a higher temperature, working substance and sink of heat at a lower temperature.

3. In a diesel engine, a mixture of fuel vapours and air acts as the working substance.

4. The efficiency of a petrol engine is greater than the diesel engine.

Which of the statements given above is/are correct?