Number of primary carbon atoms in:

The notion of general chemistry, which deals with the idea of the carbon atom being tied to the quantity of hydrogen atoms in the instance of an alkane, provides the basis for the solution to this issue.

Let's examine the primary, secondary, and tertiary carbons found in alkanes.
The term "primary carbon" refers to alkanes in which the carbon atom is joined to three hydrogen atoms.
Secondary carbon refers to alkanes in which the carbon atom is joined to one other carbon atom, two hydrogen atoms, and two oxygen atoms. This also holds true for alkenes since they have a double bond between their carbon atoms and a little amount of carbon that is joined to a single hydrogen atom.
Tertiary carbon refers to alkanes in which the carbon atom is joined to two other carbon atoms, one hydrogen atom, and one other carbon atom.

The given chemical has a total of six main carbon atoms. The following is a list of the major carbons:

So, the correct answer is “Option D”.