___ is the ideal environment for studying the effects of space on humans

Ineed to know why d is the correct answer asap

Which direction does the energy flow in this energy pyramid ?

Cattle with brown fur and cattle with white fur will produce a reddish roan calf . when examined closely, the calf show about an even number of brown hairs and white hairs that give a reddish appearance when viewed from far away. the fact that both the brown fur allele and the white fur allele are expressed equally in the offspring is an example of