Consider the following statements regarding the factors that determine the cooking temperature inside a pressure cooker:

1. The size of the vent hole through which steam escapes affects the internal steam pressure and hence the cooking temperature.

2. The temperature of the flame used mainly determines the final cooking temperature reached inside the cooker.

3. The weight and design of the pressure-regulating valve or lid governs the internal steam pressure and hence the cooking temperature.

How many of the statements given above are correct?