Could you guys help me with homework it's due tommorow

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

Which of the following are guidelines to follow for obtaining accurate observations

Select the correct answer. what does the process of natural selection involve?