Answer:
DNA does not usually exist as a single strand, but instead as a pair of strands that are held tightly together. These two long strands coil around each other, in the shape of a double helix.
I'd say C because you can't scientifically decide if a person is a good person or not
A isn't right because you can guess what's in the box by weight or sound
B isn't right because you can physically open a clock up or something to see how it works
D isn't right because you can gather data based on what food the dog takes a liking to
E isn't right because you can gather data of the nutrition of popcorn and apples
So that leaves C
Answer:
Natural air pollutants include radon, fog and mist, ozone, ash, soot, salt spray, and volcanic and combustion gases.
rain or thunderstorms
typically thunderclouds and storms are the post affect of a cold front, causing D to be your answer, MrKnowledge
