The potential energy U between two atoms in a diatomic molecules as a function of the distance x between atoms has been shown in the figure. The atoms are (a) attracted when x lies between A and B and are repelled when x lies between B and C (b) attracted when x lies between B and C and are repelled when x lies between A and B (c) are attracted when they reach B from C (d) are repelled when they reach B from A