Consider the following statements:1. Heat treatment is effective only in case of certain alloys.2. Cooling rate is an important factor in any heat treatment process.3. The temperature at which the change starts on heating the steel is called lower critical temperature.Which of the above statements are correct?

• A. 1 and 2 only
• B. 2 and 3 only
• C. 1 and 3 only
• D. 1, 2 and 3