(A) there
are now one teacher for every thirty-one students in California's elementary schools, not nearly as many than there were
"one teacher" is singular and requires singular verb "is"
INCORRECT(B) there
are now one teacher for every thirty-one students in California's elementary schools, not nearly as many as there were
"one teacher" is singular and requires singular verb "is"
INCORRECT(C) there is now one teacher for every thirty-one students in California's elementary schools, not nearly as many than there
was"not nearly as many" implies there were many teachers and requires plural "were", "was" is
INCORRECT(D) there is now one teacher for every thirty-one students in California's elementary schools, but that
ratio is much lower than
"ratio" is compared to "five years"
INCORRECT(E) there
is now one teacher for every thirty-one students in California's elementary schools, not nearly as many as there
wereHence option E