Moisture in a refrigerant system are mainly two types :
1. Visible moisture problems :       

• Freeze
• Ice crystal formation at the point of expansion
• Cap tube blocked
• Expansion valve

2. Invisible moisture problems :

• Corrosion
• ACID (Acid formation is accelerated by heat)
• Sludge
• Reduce service life and increases condensing pressure.
• High discharge pressure and temperature
• Mechanical and electrical compressor failure

To avoid this problem moisture is necessary to remove from refrigeration system, moisture removed by driers, filler driers and desiccants

Hence, the correct option is (D).