31. Of all the procedures described in the article, which of the following are effective for correcting vision without astigmatism?
(A) LASIC and INTACS
(B) INTEROCULAR LENSES and INTACS
(C) CUSTOM LASIC and INTACS
(D) LASIK and CUSTOM LASIK

第四段提到INTACS不適合散光，所以可刪除(A)、(B)、(C)。第五段提到CUSTOM LASIK矯正遠視、近視，有無散光皆適合。

There are other alternatives being explored to improve vision. INTACS are crescent shaped rings that re removable. They are placed within the cornea, leaving it intact. It works well for minimal nearsightedness, but is not effective for extreme nearsightedness, farsightedness, or astigmatism.

CUSTOM LASIK is adjusted for specific differences in an individual’s cornea, lens, and retina. IT 4 corrects both nearsightedness (sometimes to 20/20) and farsightedness with or without astigmatism.