Which one? A? B? C? D?

Which of the following explains why it took so long for the public to accept the negative health effects of smoking? a)people were waiting for counter reasons, and those were presented.b)scientists had not completely finalized their results, which took 30 years.c)cigarettes were cheaply available and media channels were very inefficient.d)cigarette manufacturers were trying hard to bring an alternative into the market

What causes the formation of ocean currents?

Holes drilled several kilometers into earth’s crust provide direct evidence about earth’s interior in the form of