Read the following sentences to find out whether there is any grammatical mistake/error in them. The error, if ant, will be in one part of the sentence. Mark the part with the error as your answer. If there is no error, mark 'No error' as your answer. (Ignore the errors of punctuations If any)
Migraines may doubles/ the risk of a / nervous system condition that/ causes facial paralysis.
(a) Migraines may doubles
(b) the risk of a
(c) nervous system condition that
(d) causes facial paralysis
(e) No error

Answer

a

Explanation

Modals take the first form of verb. So, 'doubles' should be replaced with 'double' to make the sentence correct.