In 1668, Francesco Redi performed a series of experiments on spontaneous generation. In one experiment, he began by putting similar pieces of meat into eight identical jars. Four jars were left open to the air, and four were sealed with lids. The exposed meat attracted flies, he monitored the jars and recorded whether or not maggots (young flies) appeared in the meat. What must a hypothesis be to be a viable hypothesis? It has to be testable. State a hypothesis that Redi would have been testing with his initial experiment where he was using open and sealed jars.