Read each sentence to find out whether there is any grammatical mistake/error in it. The error if any will be in one part of the sentence. Mark the number of the part with error as your answer. If there is 'No error', mark (e). (Ignore errors of punctuation, if any).
`("The power tariff has already")/a` `("been increased twice in")/b` `("the last 15 months and the Electricity Board had also")/c` `("levied additional monthly charges to consumers.")/d` `("No error")/e`

Explanation

(d) Remove .to. and use .on.