Answer: A single covalent bond is present between the carbon atoms.
Step-by-step explanation:
Carbon is the 6th element of the periodic table. The electronic configuration of this element is:

This element has 4 valence electrons and to attain stability, it cannot gain 4 electrons nor it can loose 4 electrons. Thus, it has to share 4 electrons in order to attain stability. Thus, this element forms covalent bond.
A covalent bond is formed by the sharing of electrons between two atoms.
In the question, it is given that carbon is bonded to 2 hydrogen atoms and two carbon atoms. Thus, the bond between the carbon atoms will be a single covalent bond.