Answer:
Option 3: [tex]C_{n} H_{2n-2}[/tex]
Explanation:
Alkynes are of the homologous series of acyclic (alphatic) triple bonded carbon-carbon atoms. The could be branched or unbranched chain, but the triple bonded carbons are ether attached to hydrogen atoms or a single-bond with carbon.
Thus they carry the general formula [tex]C_{n} H_{2n-2}[/tex] across the series; where n is any integer greater than 1. The simplest forms of alkynes are acetylene molecules which have the formula [tex]C_{2} H_{2}[/tex].
I hope this explanation was resourceful and easy to understand.