Vacuum distillation lowers boiling points, used for heat-sensitive compounds.

Modern propaganda theory classifies propaganda by attribution — how transparent the source is:

• White Propaganda: The source is clearly and truthfully identified. The audience knows who is speaking. Example: Voice of America broadcasting under the U.S. government's name.
• Grey Propaganda: The source is concealed or not attributed. The message is presented as coming from a neutral or independent party, making it seem more credible than if it came from an identified propaganda agency. Unsigned articles, planted stories in media, and anonymous pamphlets are examples.
• Black Propaganda: The message is falsely attributed to a hostile or enemy source, designed to embarrass that source, undermine its credibility, or provoke it into harmful actions. It is subversive and deceptive by design, typically produced by intelligence agencies. An example is forged letters attributed to enemy commanders.

Harold Lasswell defined propaganda as “the management of collective attitudes by the manipulation of significant symbols.”

1 The conclusion of the passage is that, because of safety concerns, more research and testing ought to be done before microwaves become standard household appliances. If, however, research and testing are ineffective means of discerning safety problems (as choice C says), then research and testing would be irrelevant. This criticism seriously weakens the conclusion. So choice C is the correct answer.

2 If many microwave ovens have been found to leak radioactive elements (as choice D says), then the conclusion that microwaves should not be standard appliances until they are more carefully researched and tested is further strengthened because more safety concerns need to be addressed. So, choice E is the correct answer.