Which of the following questions would NOT be an appropriate scientific question that could be tested through experimentation? Please Help
Question 4 options:

What impact does pollution have on the colors seen in rainbows

What is the most popular color?

What affect does color have on moods?

Which brand of crayons has the brightest colors?

In an old-fashioned amusement park ride, passengers stand inside a 3.0-m-tall, 5.0-m-diameter hollow steel cylinder with their backs against the wall. the cylinder begins to rotate about a vertical axis. then the floor on which the passengers are standing suddenly drops away! if all goes well, the passengers will “stick” to the wall and not slide. clothing has a static coefficient of friction against steel in the range 0.60 to 1.0 and a kinetic coefficient in the range 0.40 to 0.70. part a what is the minimum rotational frequency, in rpm, for which the ride is safe? express your answer using two significant figures. f f = rpm