Johannes wants to know whether soil, water, or both are needed for plant growth. he chooses to conduct experiments on a willow tree for five years to answer his question. how can his experimental methods be changed to improve his experiment? a. he needs to ask scientists what they think. b. he needs to conduct the experiment for a longer period. c. he needs to use a larger sample size. d. he needs to test more factors in the environment.

The correct answer is (c) He needs to use a large sample size.

Johannes needs to use a large sample size to get the results more precisely and accurately. The large sample size could have used soil in such a way that the results could have recorded more early. The time of experiment could have reduced. The large sample size could have consumed more amount of soil and water so that the results obtained by them could have been more accurate.

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.