Which of the following statements is/are correct? 1.In June 2016, the LIGO group of scientists announced the detection of a second set of gravitational waves. 2.Gravitational waves were generated due to merger of two black holes at about 1.4 billion light-years distant. 3.Gravitational waves were inserted due to collision of two white dwarf stars at about 1.4 billion light-years distant. Select the correct answer using the code given below.

• 1 only
• 1 and 2 only
• 2 and 3 only
• 1, 2 and 3