How many variables are tested in any controlled experiment?

Pl which diagram illustrates prophase?

Parthenogenesis is a type of reproduction that does not require a mate. it’s rarely seen in birds and higher vertebrates. parthenogenesis involves the formation of a zygote. but this zygote is formed without fertilization. in parthenogenesis, in the absence of a male gamete, the ovum develops directly in the zygote.

Are the layers of rock above and below the coal older or younger?