Read each sentence to find out whether there is any grammatical error in it. The error, if any, will be in one part of the sentence. The letter of that part is the answer. If there is no error, the answer is ( e ) i.e. 'No Error'. (Ignore the errors of punctuation, if any)?
The doctor helps (a)/ to reducing human suffering (b)/ by curing diseases (c)/ and improving health. (d)/ No Error (e).

Answer

b

Explanation

Here, in reducing human suffering … should be used.