The Rotational Constant of a Hydrogen Fluoride, HF, Molecule Is

The rotational constant of a hydrogen fluoride, HF, molecule is 3.12 *10¹¹ s^-1. Predict which transition in the rotational absorption spectrum will be most intense at a temperature of 400 K.

A) from J = 0 to J = 1
B) from J = 1 to J = 2
C) from J = 2 to J = 3
D) from J = 3 to J = 4