With reference to twin cyclones, Consider the following statements:1.Twin cyclones are basically caused by equatorial Rossby waves.2.Both Cyclones will always form in the Northern hemisphere.3.Among them, one will have the positive spin and the other will have the negative spin.Which of the statements given above is/are correct?

[A] 1 and 2 only

[B] 2 and 3 only

[C] 1 and 3 only

[D] 1, 2 and 3

Answer: B

Notes:

Statement 1 is correct: Twin cyclones are basically caused by equatorial Rossby waves. They are huge waves in the ocean with wavelengths of around 4,000–5,000 kilometres. This system has a vortex in the northern hemisphere and another in the southern hemisphere, and each of these is a mirror image of the other.
Statement 2 is incorrect:Recently a pair of tropical cyclones, Asani & Karim (one in the northern hemisphere and one in the southern hemisphere) one on each side of the equator, have been formed.
Statement 3 is correct: The vortex in the north spins counterclockwise and has a positive spin, while the one in the southern hemisphere spins in the clockwise direction and therefore has a negative spin.

Source: The Hindu