1,2,3, or 4. Generally, carbon likes to make 4 bonds to 4 different atoms. For example, in methane(CH4), Carbon makes 4 bonds to 4 hydrogens. However, Carbon can also make double and triple bonds to atoms. This means that of the 4 bonds, more are used to bond to one thing. For example, in the compound CN, Carbon bonds to hydrogen on one side and triple bonds to Nitrogen on the other. This shows carbon can bond to at 2 atoms as well as 4 at a time. using a one double bond carbon would only bond to 3 atoms. I cant think of an example where carbon only bonds to one other atom without breaking the octet rule, but all the other values can be validated through examples. So, I still think the bottom answer is correct. Hope this helped!
