Science is all about experimentation. The first step in the scientific process is to have a question or problem. That question must generate a hypothesis , or a testable statement. All but one of the questions listed here can generate a hypothesis. That one is:
A) Are there aliens living here on Earth today?
B) How does plant growth compare in different biomes?
C) How does the amount of space affect the wild turkey population?
D) How does the amount of fertilizer affect the growth of corn plants?