Sarah is testing different types of planting soil to determine which type is most effective in growing blueberry bushes. she purchases two different brands of planting soil from a local store. sarah applies brand a to 1 area of the yard and brand b to another area of the yard, both of which receive full sunlight. she waters the area with brand b daily; she waters the area with brand a every other day. at the end of the study, sarah concludes brand b is more effective in growing blueberry bushes. why is her conclusion not valid

Sarah's conclusion is not valid because during her testing she decided to water area A and area B differently. Therefore, she can not claim that one soil is better than another because they were put under different conditions. It is not valid. If she had treated each exactly the same, the experiment would have been valid.

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.

the correct answer is 4) heat and pressure

metamorphic rocks arise from transformation of existing rocks types, in a process called metamorphism. during metamorphism the original rock(prolith) change into metamorphic rock by heating (150-200c) and pressure of more than 1000 bar. the original rock can be sedimentary, igneous, or existing metamorphic rock.