PLS HURRY I'M BEING TIMES WILL GIVE BRAINLIEST Which best explains why an MRI is useful for diagnosing cancer but ineffective in treating it?

The frequency of the radio waves used is so high that the waves cannot be used to target specific cells.
The wavelength of the radio waves used is so short that the waves cannot be used to target specific cells.
The amount of energy carried by radio waves is enough to provide images but not enough to kill cells.
The amount of energy carried by radio waves is so high that it provides images but can also damage cells.

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