What is a boundary between geologic units called

Which sequence of transformations on preimage ∆abc will not produce the image ∆a'b'c'? a. reflection across the line y = x b. rotation 180° clockwise about the origin followed by a reflection across the line y = -x c. reflection across the x-axis followed by a reflection across the y-axis d. reflection across the line y = -x followed by a rotation 180° counterclockwise about the origin e. reflection across the y-axis followed by a rotation 90° clockwise about the origin

Ateam of researchers calculates that a glacier will melt completely away in the next 100 years. which land structure will most likely be left behind after the glacier melts?

As water is cooled from 4 c to 0 c its density