In the Mid-Nineteenth Century, Lord Rosse Built the World's Largest

In the mid-nineteenth century, Lord Rosse built the world's largest telescope, the "Leviathan of Parsonstown." What major disadvantage did Rosse have in using his telescope at this time?

A) The mirror, although large, was not made using modern techniques. It had so much distortion that deep sky objects like galaxies could not be seen clearly.
B) No catalogs of deep sky objects were available, so Rosse did not know where to locate anything of interest.
C) The telescope used an objective lens rather than a mirror and thus suffered from distortion due to sagging and chromatic aberration.
D) Photography was not available to record the images Rosse observed.