Which of the following statements best distinguishes hypotheses from theories in science? A. Hypotheses usually are relatively narrow in scope; theories have broad explanatory power. B. Hypotheses are guesses; theories are correct answers. C. Hypotheses and theories are essentially the same thing. D. Theories are proved true; hypotheses are often falsified.

A. Hypotheses usually are relatively narrow in scope; theories have broad explanatory power

Explanation:

Hypothesis are temporary explanation of an observed  phenomenon in nature. They are series  of guess to explain why an  observed characterises or features  exists or is  possible .

As an illustration; assuming  an hypothesis stated that  every dog fed   with a clean plate will  grow healthy. This is just an observation, that lead to a guess, but have not been proved with theory.(besides there are many dogs without proper care , who feed on dumps and are healthy!) Food is just one of the variable  that makes a Dog to survive there may be other variables for this! Because no experiment has been conducted to support this relationship this  hypothesis is  very narrow.

However, when experiments has  been conducted on this several times by manoeuvring the  various variables,and any unsubstantiated facts ruled out; then it can be theorized. This makes theory to be broad because it has passed through different experimental stages, scrutiny to  arrive at conclusion.

answer: the blood-brain barrier is a layer of specialized membranes and cell processes designed to keep undesirable substances from passing from the bloodstream into the precious tissues of the brain. while the blood-brain barrier does keep most bad things out of the central nervous system, it is not impermeable.

explanation: