In Alkenes There Are Four Groups Bonded to the Carbons

In alkenes there are four groups bonded to the carbons which constitute the carbon-carbon double bond. Which of the following situations produces cis-trans isomerism?

A) when all four groups are the same
B) when the two groups on one atom are the same, but the two groups on the other atom are different from each other and also different from the groups on the first atom
C) when three of the four groups are the same, but the fourth group is different
D) none of these results in the existence of cis-trans isomerism