Select the most appropriate option to substitute the underlined segment in the given sentence to make it a meaningful sentence. If no substitution is required, select ‘No substitution’.

Patients who do previous heart attacks and those with cardiac failure are at a higher risk of having a cardiac arrest.

A

who have had previous heart attacks and those with cardiac failure are at a higher risk of having

B

who have had previous heart attack and they with cardiac failure are at a higher risk of having

C

who have had previous heart attacks and those of cardiac failure are at a higher risk of having

D

No substitution