How are gas-phase reaction rates commonly expressed when using pressures instead of concentrations?

• A. Rates are always expressed in terms of concentration, not pressure.
• B. Rates depend only on temperature, not on pressure.
• C. For ideal gases, concentrations are proportional to partial pressures; rate laws can be written in terms of p_A, p_B with appropriate exponents.
• D. Rate laws cannot be written in terms of pressure.

Answer: (C)