Answer
The IUPAC name of the alkyne is $1-cyclopentylbut-2-yne$
Work Step by Step
The compound has 4 carbon atoms in its longest carbon chain containing the triple bond(but−). It has a $cyclopentyl$− substituent at position 1 and a triple bond at position 2. So, the IUPAC name of the alkyne is $1-cyclopentylbut-2-yne$