Which choice most logically completes the text?

Source Texts

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Careful planning was essential for the success of the Deep Impact probe, which conducted a flyby of comet 9P/Tempel and then traveled to comet 103P/Hartley. The CONTOUR probe mission seemed similarly well planned, but engineers lost communications with the probe before it could achieve the mission goal of visiting comet 73P/Schwassmann-Wachmann. This shows that ______

the Deep Impact was more successful than the CONTOUR because it had fewer tasks to accomplish.

having multiple mission goals ensures that a probe will accomplish at least one of its tasks.

the CONTOUR would likely have accomplished its tasks if it had been sent somewhere other than comet 73P/Schwassmann-Wachmann.

careful planning alone does not guarantee that a probe will accomplish its mission.