TOEFL Grammar - Find the error

in TOEFL Test
Find the error in the underlined words in the following sentence:
Rapid population growth coupled with ageing infrastructures has put strain on the water resources - fresh water and waste water treatment - in many Chinese cities.A. coupled with
B. has put strain
C. fresh water
D. in many Chinese
Click here for the right answer:
Rapid population growth coupled with ageing infrastructures has put a strain on the water resources - fresh water and waste water treatment - in many Chinese cities.
Tagged: