Which of the following are responsible for occurrence of critical or whirling speed of shaft? 1. Eccentric mounting of the rotor2. Non-uniform distribution of rotor material3. Bending of shaft due to the weight of the rotor and the shaft itself4. Environmental effect such as effect of moisture and temperatureSelect the correct answer using the code given below.

• A. 1, 2, 3 and 4
• B. 1, 2 and 3 only
• C. 1, 2 and 4 only
• D. 1 and 3 only