Which refers to information gathered by the systematic study of nature? prediction
communication of facts
scientific knowledge
hypothesis

It is d, all the other ones say incorrect answer .

Answertraveling around a circular trackexplanation"traveling around a circular track" is the best answer as you could be traveling around a circular track at a constant speed. your velocity would therefore have the same magnitude but will always be constantly direction. since acceleration is the rate of change of velocity, the rate of change will only involve the direction of velocity and not the magnitude.wrong choices: "an object at rest" does not accelerate at all"increasing speed while traveling around a curve" means that the acceleration will not be constant due to only change in direction; it will be constant due to both magnitude and direction"an object in free fall" does not necessarily change direction 

We can infer that star y is closer but other factors must be considered include the heat of the star, the mass, and the brightness of the star. even though star x seems dimmer it may just be less bright or contains less heat.