Asmall group of four singers is singing a hymn in four-part harmony. each singer is always singing a different pitch, but the rhythms for all four singers are the same. what is this texture called?

It’s a homophony texture :) hope this helps!

Generally spontaneous human combustion is something that still bewilders some, human combustion happens very rarely and doesn't affect the surrounding areas, so unless you want to set your self on fire, human combustion will remain spontaneous and very rare.