Which sentence best introduces the author’s consideration of an alternate or opposing opinion? Answer choices for the above question

A. “Manned programs can cost tens or hundreds of times more than the robotic missions.”

B. “There are three important goals we need to achieve from our space program.”

C. “The final goal is that of making humanity a multiplanetary species.”

D. “Developing human space-faring technology is crucial, but first we need to decide where to go.”