Read the excerpt from "Exploring Mars.” For years, people talked about the canals on Mars. Some thought Martian farmers dug them to water their crops. But later, scientists made better telescopes. They saw that the lines didn't even exist. They were just illusions. Which best states the central idea of this excerpt? Some people believed Martians used canals the same way Earth people do.
Newer telescopes helped scientists see the surface of Mars better.
Sometimes people think they see things, but they are only seeing illusions.
People thought there were canals on Mars, but it turned out there were none.

laughter and happiness are an essential part of life. laughing releases the body's "feel good" chemicals. thus, it provides long or short term relief from stress and or anxiety. more or less, laughing strengthens social connections and provides an easy approach in social related situations.

moreover, there are many benefits of laughter and humor. it's as if they play the role of superhero to combat anxiety and depression, according to researchers. happiness and laughter is the best medicine for teen mental health.

what happens in the body also affects the mind. the positive changes in physical health also have profound an impact on mental health. we have a lot to gain from laughing! medical effects of laughter have continued to validate the pain-relieving effect and benefits of laughter.

scientists tell us that laughter and humor actually, believe it or not, lower blood pressure, reduce stress hormones and increase muscle flexion. there are many benefits to happiness and laughter, and they so happen to increase the circulation of antibodies in the blood stream and make us resistant to infections.

as stated before, laughing releases your body's "feel good" chemicals, and on a related note, negative stress can cause your body to release chemicals that weaken your immune system which makes you more likely to contract a disease. luckily, laughter reduces negative stress and prevents those chemicals from being released.

all in all, you may want to consider laughing as much as you can!

b is the correct answer

. a function is a relation in which each input has only one output. in the relation , y is a function of x, because for each input x (1, 2, 3, or 0), there is only one output y. x is not a function of y, because the input y = 3 has multiple outputs: x = 1 and x = 2.