Which of the following is the brightest planet of the solar system?

The brightest planet in our solar system is Venus. Often referred to as the "Evening Star" or "Morning Star," Venus is the third-brightest object in the sky after the Sun and the Moon. 

This exceptional brightness is primarily due to its dense atmosphere, which is rich in carbon dioxide and covered by thick clouds of sulfuric acid. These clouds reflect a significant portion of sunlight, causing Venus to shine brightly when observed from Earth. 

Final Answer

Answer: c) Venus