An object 5 millimeters high is located 15 millimeters in front of a plane mirror. how far from the mirror is the image located?

For a plain mirror the image distance is the same as the object distance therefore the image will be 15mm at the back of the mirror.

The rocks expand when there hot/warm  and contract when they are cold.

The best answer is (a) which is universal law is in effect at all times. it is constantly at play in everything we do and governs our lives. it is also important to note that universal law applies to not only everything on earth, but everything in the universe as well, which is another reason why it is in effect at all times.