Step 1: Analyzing the structures.
The two molecules shown in the image are organic compounds that differ in their spatial arrangement around the stereocenters. Let's examine their relationship based on stereochemistry.
Step 2: Understanding the options.
- (A) Correct: These molecules are stereoisomers because they have the same molecular formula and connectivity of atoms but differ in their spatial arrangement of atoms, which makes them stereoisomers.
- (B) Incorrect: The two molecules shown each have only one stereocenter, not two. A stereogenic center is a carbon atom bonded to four different substituents.
- (C) Incorrect: The molecules are not mirror images of each other. Mirror images are enantiomers, but these molecules are not enantiomers because they are not related by reflection in a mirror.
- (D) Correct: These molecules are diastereoisomers. Diastereoisomers are stereoisomers that are not mirror images of each other. Since the two molecules are not mirror images but differ in their spatial arrangement, they are diastereoisomers.
Final Answer:
\[
\boxed{\text{(A) and (D) are correct.}}
\]