The following sentence has been divided into parts. One of them may contain an error.
Select the part that contains the error from the given options. If you don’t find any error, select ‘No error’ as your answer.
The air in the city is so polluted / that it will be causing / several kinds of respiratory illnesses.

A

several kinds of respiratory illnesses

B

No error

C

The air in the city is so polluted

D

that it will be causing