Final answer:
The circled carbon atom is bonded to three hydrogen atoms, and because carbon forms a total of four bonds, no additional hydrogens are connected to the circled carbon beyond these three.
Step-by-step explanation:
In the given structure, each carbon atom is bonded to four other atoms or pairs of electrons, as carbon tends to make four bonds to achieve a full outer shell of electrons. If we examine the structure where the carbon is bonded to three hydrogen atoms and a nitrogen, we can deduce that the circled carbon already has four bonds (three to hydrogen and one to nitrogen), and therefore, no additional hydrogen atoms are connected to it beyond the three mentioned.
To break it down, a carbon bonded to three hydrogens and one nitrogen means that it's got a total of four bonds. Carbon’s valency is four because it has four valence electrons, so it tends to form four bonds to fulfill the octet rule. Since the carbon in question is already forming these four bonds, it cannot accommodate more hydrogens.
The nitrogen mentioned is double bonded to another carbon, and this second carbon is also double-bonded to an oxygen, which is the typical structural representation of a carbonyl group. The nitrogen has one lone pair, and the oxygen has two lone pairs, which are not bonded to any other atoms.