Can somebody please help me with these 3 questions ? and explain them so I can understand them

Explanation:
1. The group of atoms above bonded together is
called a molecule.
Therefore,
Option A is correct ✔
2. There's 4 H-atom in 2H₂O
Therefore,
Option A is correct ✔
3. There's 2 molecules in 2Al₂O₃
Therefore,
Option A is correct ✔