How do you represent a triple bond in a structural formula?
(A) Three horizontal lines
(B) =
(C) –
(D) ***
(E) Four horizontal lines

Hint: Double bond has two horizontal lines. One of them is a sigma bond and the other is pi-bond.

Complete step by step answer:
Let us first concentrate on the concepts of bonds between the carbon atoms;
Saturated hydrocarbons-
Hydrocarbons that contain only a single bond between the carbon atoms are the saturated hydrocarbons. They are the simplest class of hydrocarbons as the carbon atom is attached to the hydrogen atoms only and are bound with a bond.
Generally, they are called alkanes. They involve one electron pair $\left( C-H \right)$

Unsaturated hydrocarbons-
The carbon atoms in the hydrocarbons may share a double or triple bond within themselves. These are called unsaturated hydrocarbons.
Generally, they are alkenes, alkynes, or aromatic hydrocarbons.

Considering, a double bond-
As the name suggests, they have two bonds represented by two horizontal lines. One of them is sigma bond (which is stronger) and the other one is pi-bond (weak bond).
These are called alkenes. They involve two electron pairs $\left( C=C \right)$.

Similarly, a triple bond has three bonds represented by three horizontal lines. One of those is the sigma bond. The other two are the pi-bonds which are weaker and can be cleaved by hydrogenation.
These are the alkyne groups. They involve three electron pairs $\left( C\equiv C \right)$.
Thus, the triple bond has three parallel horizontal lines.
So, the correct answer is “Option A”.

Note: Option (D) *** can never be correct as such notations are not involved in the hydrocarbons.
Also, option (E) cannot be the answer as four horizontal lines would represent four bonds between the carbon atoms, which is impossible.