Identify the correct combination of the following statements.
P. Hydrogen electrode is a standard used to measure redox potentials.
Q. Activation polarization refers to electrochemical process controlled by reaction sequence at metal-solution interface.
R. Potential-pH diagrams can be used to predict corrosion rates of metals.
S. Cathodic protection can use sacrificial anodes such as magnesium.

A. P, Q and R

B. Q, R and S

C. P, Q and S

D. P, R and S

Answer: Option C