With cloning technology, researchers are approaching what has long been the ultimate goal of modern botany: achieving an exactness of quality and appearance in hothouse plants as once thought to be limited to manufactured items.
(A) achieving an exactness of quality and appearance in hothouse plants as once thought to be
- as once thought to be is not idiomatic
(B) achieving hothouse plants with an exactness of quality and appearance as were once thought of as
- same problem as A
(C) achieving in hothouse plants an exactness of quality and appearance that was once thought to be
- I'll take C. achieve the quality in a certain prodcut (hothouse plant) and 'that was once thought to be' is the correct way to phrase the sentence
(D) achievement of hothouse plants whose exactness of quality and appearance are the same as what were once thought to be
- achievement of hothouse plants changes the meaning
(E) achievement of hothouse plants at an exactness of quality and appearance once thought of as
- achievement of hothouse plants changes the meaning
C it is