What is the effect of cyanide and carbon monoxide on cytochrome a in the electron transport chain?

• A. They block electron flow at cytochrome a, preventing the conversion of oxygen to water.
• B. They block electron flow at cytochrome c, preventing the conversion of oxygen to water.
• C. They inhibit the citric acid cycle, reducing the production of NADH and FADH2.
• D. They increase electron flow at cytochrome a, enhancing the conversion of oxygen to water.

Answer: (A)