Which of the Following Statements Is True of Voting Requirement

Which of the following statements is true of voting requirement? 

A)  All voters should have completed twenty-one years of age. 
B)  Voters should be citizens of the United States. 
C)  Voters should abide by a residency requirement of at least sixty days. 
D)  Noncitizens will need to take the president's permission to cast their vote. 
E)  To be exempted, a voter needs to produce a medical certificate.