Briefly explain the following;

(a) How would you know a Refrigeration System is Undercharged? (4)

(b) What should you do to ensure that there is no Water Leakage into the Engine Cylinder before preparing Main Engine for Sea? (6)

(c) What would cause the Level of the Lub Oil Sump of Main Engine or Drain Tank to Rise? (4)

(d) How can Exhaust Valve Leakage of Auxiliary Engine be confirmed? (2)