Prompt: The test tube held the remnants of the debris of the experiment. The test tube 
Completion A: awaits the arrival of Elon Musk's new business, which promises to transport riders via an underground tube at high speeds but has yet to be rigorously tested. 
Completion B: went to the church later that week. 
Completion C: fell down the mountain, since it was unable to ski well. 
Completion D: was cleared of the remnants with filtering.
Completion D