One Way to Distinguish a Star from a Planet, Particularly

Multiple Choice

One way to distinguish a star from a planet, particularly when they appear near the horizon, is that stars appear to twinkle and planets shine steadily. Which of these statements is a reasonable explanation for this phenomenon?

A) Stars actually do twinkle-shine with a light that flickers bright and dim-whereas planets shine with a steady, unwavering light.
B) The light from planets is so much brighter than the light from stars (when they are observed from Earth) that it is unaffected by air movement in Earth's atmosphere.
C) The disk of a planet, as observed from Earth, appears larger than the disk of a star. Thus, if refraction through moving air in Earth's atmosphere makes the planet's disk appear to move about slightly, there will normally be a central part of the disk that shines steadily and does not appear to twinkle.
D) Because light from planets is reflected, it is unaffected by the refraction in Earth's atmosphere.