The Hubble telescope has the great advantage over land-based telescope

The Hubble telescope has the great advantage over land-based telescopes of taking images from outside of the planet's atmosphere, which greatly blurs images. Nevertheless, the Hubble has two major disadvantages relative to land-based telescopes: it is difficult to repair, and to maneuver it requires the use of fuel, which will ultimately run out. An advisor at the space agency has proposed equipping the International Space Station with small robotic spacecraft that can be launched from orbit to repair the Hubble at a much lower cost than a repair craft launched from earth would cost.

Which of the following, if true, is NOT a serious weakness of the space agency advisor's plan?

[A] While in flight, the robotic spacecraft are roughly as likely to break down and require repairs as the Hubble, and they are not capable of repairing each other.

[B] The robotic spacecraft will themselves need fuel and will require fuel to be sent from Earth at a total cost comparable to that of launching repair craft from Earth.

[C] The robotic spacecraft proposed by the advisor will incur significant design costs not incurred by a repair craft launched from earth, which already exists.

[D] To be effective, the proposed robotic spacecraft may require human maintenance on the International Space Station when all astronauts aboard are committed to other uses of their time.

[E] The robotic spacecraft will not have the capability to refuel the Hubble.