Which of the Following Best Describes a Double-Blind Study

Which of the following best describes a double-blind study?

A) neither participants nor researchers know who is receiving placebo or receiving the treatment
B) 50% of participants receive a placebo and 50% receive treatment but no individual knows what they are receiving
C) participants are told what condition they are receiving but researchers are not told so that they analysis of results cannot be skewed
D) 25% of participants receive the treatment while 75% receive the placebo after being matched for randomization in small groups