Why Should One Not Stare at the Sun During an Eclipse

Why should one not stare at the Sun during an eclipse?

A) because, whether there is an eclipse or not, the Sun's intense radiation can easily damage our eyes
B) because the eclipse event itself creates a lensing effect, which greatly magnifies and intensifies the Sun's rays
C) because Sunspots, which are excited by the eclipse event, can easily erupt during the eclipse
D) because ultraviolet radiation is intensified during the event
E) because coronas and corneas are always a bad mix