The term cell was coined by Robert Hooke. The studies he was building of was the work of Van Leeuwenhoek.
<h2>
Fighting for Clean Air in our National Parks</h2>
Air pollution is one of the most serious threats facing national parks, harming visitors’ health, clouding scenic views and altering our climate.
The air pollution affecting national parks — and the rest of the country — results from the burning of fossil fuels by power plants, oil and gas development, vehicles, agriculture, industrial emissions, and other sources. NPCA works to make sure our nation’s air laws are strong, to hold polluters and government accountable to those laws, and ultimately, to reduce the air pollution that harms our parks, climate and communities.
<h2>Defending Federal Laws and Regulations
</h2>
The Clean Air Act – which has helped improve air quality throughout the nation and the National Park System – is now under consistent threat as the Environmental Protection Agency works to roll back regulations, attack the use of science and offer polluters loopholes. NPCA advocates to defend and strengthen the clean air laws that protect park skies. We speak out for science and guard against policies driven only by politics and private industry.
<h2>Holding Polluters and Governments Accountable
</h2>
Picture park skies free of pollution. While this sadly isn’t the case today, NPCA strives to make sure that parks are on the right track and that air pollution harming parks is reduced. We do this by helping to secure strong state plans to limit haze-causing and climate-altering pollution, and by defending existing plans – in court, if necessary.
<h2>Advocating for Pollution Reduction</h2>
Clean air laws are meaningless if polluters and the government don’t follow them. NPCA vigilantly monitors for sources that violate their permits or when officials aren’t following through on the safeguards in place to protect parks. We also look for opportunities to collaborate and work in state, local or regional processes to prevent threats of new pollution and help reduce harmful emissions. Learn about our work in California and Utah.
The have tube feet and and they have no organs or eyes
Answer: c. Prospective cohort study
Explanation:
Prospective cohort study is a type of observational study which is used to study large number of subjects which are similar but vary with respect to certain factors required to be considered under the study. This is done to determine how these factors affect the rates of certain outcomes. The subjects are studied under different frames.
Here, in the given study the subjects are the same which is a group of middle aged men. These are at a risk of premature ventricular contractions thus are at greater risk of myocardial infraction as compared to men those heartbeats are regular. Here there are different factors to be observed upon and the subjects are also studied in different time frames thus this condition is an example of prospective cohort study.
