Answer:
single bond
Step-by-step explanation:
Single bond is the chemical bond in which 2 valence electrons are involved. These are the sigma bond which are formed formed by the head-on overlapping between the orbitals of the two atoms involving in the bond. The bond lies on the inter nuclear axis and thus , the bond can be rotated without the breaking of bond.
On the other hand, double and triple bonds contains one sigma bond and also bonds which are formed by the sideways overlapping of the orbitals and thus, these do not lie on inter nuclear axis and breaks on rotation.