Which sequence furthers scientific knowledge?

A.Hypotheses generate a scientific question, leading to observations, which can be tested through an experiment.
B.Observations generate a scientific question, leading to a hypothesis, which can be tested through an experiment.
C.Hypotheses generate a scientific experiment, leading to observations, which can be tested through a question.
D.Observations generate a scientific experiment, leading to a hypothesis, which can be tested through a question.