Your choice (saturated aqueous NaHCO₃) is

(It is also correct if you choose dilute aqueous NaOH.)

• You see two layers (phases*) in the separatory funnel because water and dichloromethane are immiscible*.
• The aqueous phase is the top layer because water is less dense* than dichloromethane.

What is your next step?

Separate the layers
Cautiously shake the separatory funnel