Question

cis - trans isomers not isomers structural isomers conformational isomers

Explanation:

Step1: Analyze isomer types

Conformational isomers are different spatial arrangements of the same molecule that can be inter - converted by rotation around single bonds. These two structures can be interconverted by rotation around single bonds.

Step2: Rule out other options

• Cis - trans isomers require a double bond or a ring structure with restricted rotation and different groups on either side of the double bond or ring in a specific geometric arrangement, which is not the case here.
• They are isomers since they have the same molecular formula and different arrangements, so “not isomers” is incorrect.
• Structural isomers have different connectivity of atoms, but here the connectivity is the same, just the spatial arrangement due to bond - rotation is different.

Answer:

D. conformational isomers