This is my question please help

For a comparative or experimental investigation, scientists often make a testable about a scientific question, and then they test it in the investigation. a. control b. hypothesis c. procedure d. system

What do isotopes of uranium have the same number of? what do they have a different number of? a) same number of protons; different number of electrons b) same number of protons; different number of neutrons c) same number of electrons; different number of protons d) same number of neutrons; different number of protons

Why did adult crab numbers decline in he ecosystem, even though sea stars were still available?