Select the correct chronological order of the following events connected with India’s struggle for independence from the code given below:

1. Second Round Table Conference

2. Karachi Session of Indian National Congress

3. Execution of Bhagat Singh

4. Gandhi-Irwin Pact

Code :

U.P.P.C.S. (Mains) 2013 U.P. P.C.S. (Pre) 2009 U.P. P.C.S. (Mains) 2006