Part A:
The correct answer is:
A. The dollar cost of sending men into space is a factor that both authors mention, but see the financial investment of that idea in different ways.
Part B:
The correct answer is:
D. If sending one human crew to Venus could advance our knowledge of the universe as much as three robotic space missions could, even a much higher cost would be justified.
This sentence reflects a different interpretation of the financial implications and benefits of sending humans into space compared to the perspective presented in the first text, which emphasizes the cost-effectiveness of robotic missions.