At the Start of the Triassic,most of the Continents Were

At the start of the Triassic,most of the continents were above sea level,and sediments from that time are often red because ________.

A) they contain extensive deposits of iron ore
B) they are a major source of uranium and red quartz
C) they include iron oxides
D) the dry climate baked clays to form hornfels
E) there are extensive dune fields