Answer:
sentence 6
Explanation:
A hypothesis is a supposition or proposed explanation that is made by observing such evidence. The hypothesis is the start point of further investigation. The scientific method is demonstrated by the sentences:
Sentence 1 represents the problem, or the research question: why sea water freezes at a lower temperature than fresh water?;
Sentences 2 and 3 represent the initial research;
Sentences 4 and 5 represent the observation;
Sentence 6 is the hypothesis;
Sentences 7, 8 and 9 are the experimental phase, and
Sentence 10 is the theory: hypothesis was tested and proved in the experiment.
