and  are :A Identical  B Enantiomer C Diastereomer D Functional isomer

The options given, A, B, C, and D, represent different types of relationships between two compounds. To determine the correct answer, we need to understand the definitions of each type of relationship.

1. Identical (A): Two compounds are considered identical if they have the same molecular formula and the same connectivity of atoms. In other words, they are exactly the same in terms of their chemical structure.

2. Enantiomer (B): Enantiomers are a type of stereoisomer. They are mirror images of each other and have the same molecular formula and connectivity of atoms. However, they differ in their spatial arrangement, specifically in the way they rotate plane-polarized light.

3. Diastereomer (C): Diastereomers are also stereoisomers, but unlike enantiomers, they are not mirror images of each other. They have the same molecular formula and connectivity of atoms, but differ in their spatial arrangement at one or more stereocenters.

4. Functional isomer (D): Functional isomers have the same molecular formula but differ in the functional groups or the way the atoms are connected. They have different chemical properties due to these differences.

Now, based on the given options, we need to determine which type of relationship best describes the compounds in question. Unfortunately, the compounds themselves are not provided, so we cannot determine the correct answer without more information.

To answer the question, we would need to know the specific compounds being compared and analyze their molecular formulas, connectivity of atoms, spatial arrangement, and functional groups.