Which is the best way to write the underlined portion of this sentence?

— ExhibitC

Sentence 10:Furthermore, in almost 90 percent of the CO calls reported to utilities and fire departments in the mid-1990s, the levels found were to low to affect the average person.

Which is the best way to write the underlined portion of this sentence? If the original is the best way, choose optionA.

A. to low to affect

B. to low to effect

C. to low, to affect

D. too low to effect

E. too low to affect

Answer: E