When astronomers observed the comet Schwassman - Wachmann 3 becoming 1, 000 times brighter in September 1995, they correctly hypothesized that its increased brightness was a result of the comet' s breaking up -- when comets break up, they emit large amounts of gas and dust, becoming visibly brighter as a result. However, their observations did not reveal comet Schwassman-Wachmann 3 actually breaking into pieces until November 1995, even though telescopes were trained on it throughout the entire period. Which one of the following, if true, most helps to resolve the apparent conflict in the statements above? ['The amount of gas and dust emitted steadily increased during the period from September through November.', 'Gas and dust can be released by cracks in a comet even if the comet is not broken all the way through.', 'Comets often do not emit gas and dust until several weeks after they have begun to break up.', 'The reason comets become brighter when they break up is that the gas and dust that they emit refract light.']