Read each sentence to find out whether there is any grammatical error or idiomatic error in it. The error, if any, will be in one part of the sentence. The number of that part is the answer. If there is no error, the answer is (5).
(Ignore errors of punctuation, if any)
Our Chairman is deeply concerned (1)/about the environment (2)/and plans to take some steps to reduce the (3)/pollution caused by our factories. (4)/No error (5)