In the following passage, some words have been deleted. Read the passage carefully and select the most appropriate option to fill in each blank.

When the air is clear, the sunset (1)______ yellow, because the light from the sun has passed a long distance through air and the blue light (2)______ scattered away. If the air is polluted with small particles, natural (3)______ otherwise, the sunset will be more red. Sunsets over the sea may also be orange, (4)______ salt particles in the air. The sky (5)______ the sun is seen reddened, as well as the light coming directly from the sun.