Read the sentence to find out whether there is any grammatical or idiomatic error in it. The error, if any, will be in one part of the sentence. The corresponding letter of that part is the answer. If the given sentence is correct as it is, then choose option ‘No error’ as the answer response. (Ignore errors of punctuation, if any).

When the author writes (A)/ his stories, he tries to include (B)/ a mortal lesson that will (C)/ resonate with his readers (D)/ no error (E).

Correct option is A

The error lies in part (C) of the sentence.
This phrase is incorrect because " mortal" means relating to death or causing death, which doesn't make sense in the context of the sentence. The correct word should be "moral," which refers to a lesson or principle about right and wrong.
Thus, “mortal” should be replaced with “ moral”.
Hence, the correct sentence formed will be “When the author writes his stories, he tries to include a moral lesson that will resonate with his readers."