Final answer:
In the context of the paragraph, 'plume' refers to a trail of material ejected into the air following the impact of the rocket on the Moon, making the correct answer B) Trail.
Step-by-step explanation:
The term 'plume' in Paragraph 4, which states "The Centaur rocket plunged into the moon and sent up a plume...", refers to a column of material that rises into the air as a result of an event such as an impact or explosion. In this context, the plume would consist of lunar material and possibly other substances ejected by the impact of the rocket on the Moon's surface. Thus, the correct answer is B) Trail, which relates to a visual representation of the material thrown up into the air. It is not A) Smoke, which is specific to the product of combustion, nor C) Explosion, which is an event rather than a byproduct, and not D) Water, which would be a specific substance not implied by the use of the term 'plume' alone.