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(d).
`("The oxygen content of Mars is not")/a` `("sufficient enough to support life")/b` `("as we know it.")/c` `("No error")/d`.

Explanation

(d) No error