Diabetes, together with its serious complications,
ranks as the nation's third leading cause of death, surpassed only by heart disease and cancer
(a) ranks as the nation's third leading cause of death, surpassed only
(b)
rank as the nation's third leading cause of death, only surpassed
(c) has the rank of the nation's third leading cause of death, only surpassed
(d)
are the nation's third leading causes of death, surpassed only
(e)
have been ranked as the nation's third leading causes of death, only surpassed
Subject -> Diabetes -> Singular
Remove the words between the 2 commas and then read it.
One will notice that a singular verb will follow singular subject, which is happening in two options
a and c .
Now between 'a' and 'c', will it be surpassed only or only surpassed ??
Surpassed only in 'a' means that only two diseases will surpass diabetes, whereas in 'c' only surpassed means that there can be more diseases than the mentioned two.
Giving the answer as
a