Which of the following will have zero dipole moment ?

Trans 1,2 di-chloroethylene will have zero dipole moment because, in the structure of the compound ,the two chlorine and hydrogen atoms orient in opposite way on adjacent carbons and cancel each other. Thus it will have zero dipole moment.
In other words, In trans isomer, two electronegative chlorine atoms are opposite to one another, as such the resultant dipole moment is zero.

Hence , the correct option (C) . trans -1,2 - dichloroethylene