padi IDC theory – SCUBA equipment

Q4
The second stage of a regulator works as follows:
b)   A diaphragm opens a valve releasing air from the first stage

Q5
An environmental seal is used for?
a)    Greenpeace advertisements
b)   Regulators used in cold water environments
c)    Preventing the second stage from freezing
d)   Both “B” and “C” are correct