The correct relationship between the two faces of the C=O group in compounds A and B is

Concept:

Enantiomers : 

• Enantiomers  are a pair of molecules that exist in two forms that are mirror images of one another but cannot be superimposed one upon the other.
• Have identical physical properties except for the ability to rotate plane-polarised light.

Diastereomers : 

• Diastereomers are defined as compounds with the same molecular formula and sequence of bonded elements but are non-superimposable non-mirror images.
• They have distinct physical properties. Diastereomers are stereoisomers with two or more chiral centers that are not enantiomers.
• Enantiomers and diastereomers are the only two stereochemical relationships that you can have between any two molecules.

The stereoisomers are any two molecules that fulfill the following two requirements: Both molecules must have the same molecular formula, and. Both molecules must have the same atom connectivity.

Explanation:

This structure A is having sp³ hybridized carbon on which oxygen is present due to which it can rotate thus it is diastereotopic in structure B there is a plane passing through the centre of the bridge and it will produce a non-superimposable mirror image thus it is enantiotopic. 

Conclusion: option A is correct.