Answer:
A. Neither the subjects nor the researchers can bias the results.
Explanation:
As described, a double- blind study is one in which the researcher and his study does not know the person receiving the actual treatment.
Researchers can be bias in their studies as they seek to establish and fine tune results in the way the best favors them. A double-blind study helps to bridge this gap to prevent bias that might be introduced into an experimental set up or while interpreting results.
Answer:
All of the above.
Explanation: Their particles are so close packed together.
6.3 ×

In scientific notation, the numerical value without the exponent of 10 must be within the range from 1 to just below 10 (for example, 9.99...). In this case, 6.3 is already within this range, so we just have to multiply it by 1. To get a multiplier of 1 using base 10, we would have to raise 10 to the zeroth power.