How do identical twins form?
a. a fertilized egg splits in two.
b. two eggs are fertilized by one sperm.
c. two eggs are fertilized by two sperm.
d. two sperm fertilize an egg

Disinfection of impression materials is usually accomplished by a. sterilization with high heat. b. spray or immersion in a chemical disinfectant. c. sterilization with steam under pressure. d. allowing the impression to sit 24 hours in water until all the organisms die.

What claim did thorne make? what evidence supported his claim?

Look at the picture below . what does this picture represent ?