Concept:A planet's brightness in our sky depends on how close it is to the Earth and the sun and how much sunlight it reflects.Explanation:Venus is the planet that comes closest to the Earth, and its thick white clouds reflect about 75% of the sunlight falling on it. So it is the brightest planet, and after the sun and moon the brightest object in the sky (the 'morning star' or 'evening star').Answer:Option D (Venus)