# Which of the following molecule has the lowest dipolemoment?

$\begin{array}{1 1}(a)\;CH_2=CHC\equiv CH\\(b)\; CH_3CH_2C\equiv CH\\(c)\;CH_3-CH=CH-CH_3\\(d)\;CH_3C\equiv CCH_3\end{array}$

This molecule has zero dipolemoment .Because it has plane of symmetry.
Hence (d) is the correct answer.