But-2-ene exhibits cis-trans-isomerism due to
(a) rotation around C2-C3 double bond
(b) rotation around C3-C4 sigma bond
(c) rotation around C1-C2 bond
(d) restricted rotation around C=C bond
(d) Due to presence of >C=C< in butene-2, it shows restricted rotation. Hence, give two types of arrangements around the space of >C=C< as cis and trans-forms.