In the following question, there is a sentence which is divided into four parts. Choose the fragment that carries an error (if any). Ignore punctuation errors if any.
In case an informal system is used, / either a transfer, an informal warning / or a non-hierarchical but status demotion / are the remedies to correct indiscipline.
either a transfer, an informal warning
'either' is used with 'or'. Hence, the sentence should be 'either a transfer or an informal warning'.