Identify the error part in the sentence: Either my brothers (a) / or my friend (b) / are coming to receive me at the airport. (c) / No error. (d)

The error lies in part (c). In an 'either...or' construction, the verb agrees with the subject closest to it (proximity rule). Since 'my friend' (singular) is the subject closer to the verb, the verb should be 'is coming' rather than 'are coming'. The correct sentence is: 'Either my brothers or my friend is coming to receive me at the airport.'