Why is the correct answer (A)?

The first SAT of the season is coming up soon (not to mention the PSAT)! Luckily all of our students have been keeping up with their practice problems. Like, for example, today’s official SAT question of the day:

The following sentence contains either a single error or no error at all. If the sentence contains an error, select the one underlined part that must be changed to make the sentence correct. If the sentence contains no error, select choice E.

Between 1508  to  1512, Michelangelo,  working on
A B
a scaffold 60 feet above the floor, painted the
vaulted ceiling of the Sistine Chapel in Rome
with hundreds of
 giant figures  that represented
C D
his vision of the world’s creation.   No error
E

How’d you do?