Why do sunlight harm certain types of vampire?

Why though?

Ultraviolet light or some other electromagnetic waves from the sun
Votes: 0 0.0%
Some holy properties of the sun
Votes: 3 25.0%
Both of those
Votes: 2 16.7%
Some combination of both
Votes: 1 8.3%
Vampires are superstitious that the sun is harmful to them
Votes: 5 41.7%
Someone cursed the vamps to be harmed by sunlight
Votes: 1 8.3%