A stuffing box:
1. stops air leaking into the casing when the pressure is below atmospheric
2. decreases leakage out of the casing when the pressure is above atmospheric
3. is always supplied with a lantern ring
4. is filled with packing
a) 1, 3
b) 1, 4
c) 2, 3
d) 2, 3, 4
e) 1, 2, 4
Answer: E