Select the correct option based on the statements below:

Assertion (A): The geometry of formaldehyde molecule is planar.
Reason (R): Formaldehyde molecule contains sp2 hybridized carbon atom.
  
1. Both (A) and (R) are True and (R) is the correct explanation of (A).
2. Both (A) and (R) are True but (R) is not the correct explanation of (A).
3. (A) is True but (R) is False.
4. Both (A) and (R) are False.
Hint: In a molecule, all of its atoms lie in the same plane.
Formaldehyde is a planar molecule because all of its atoms lie in the same plane. It is due to sp2 hybridized carbon atoms, present in formaldehyde.
The structure is as follows:
Hence, an option first is the correct answer.