All the things that have to stay the same in an experiment are

constants

Explanation:The factors that can change value during an experiment or between experiments, such as water temperature, are called variables, while those that stay the same, such as acceleration due to gravity at a certain location, are called constants.

i think that it is plants

glacial erosion, the picking up and movement of earth beneath a glacier, is also referred to as plucking. erosion and transportation of individual pieces of bedrock, especially large "joint block occur as a result of this glacial erosion. plucking is type of erosion in which rocks become frozen into the bottom and sides of the glacier.as the glacier moves downhill it 'plucks' the rocks frozen into the glacier from the ground.