Answer:
A. a description
Step-by-step explanation:
The passage is actually a description. The speaker describes the personality and passion of the Challenger crew.
The speaker stated in his description that they were daring, brave and possessed special grace. He further describes the type of passion they had; one that wished to serve. They were hungry to explore the universe. The speaker also describes the crew as pioneers.
So, the primary text structure is a description.