Directions: In the following question, some part of the sentence may have an error. Find out which part of the sentence has an error and select the appropriate option. If a sentence is free from errors, select option 'No error'.

The head of the National Institute of Allergy /(A) and Infectious Diseases have served /(B) six presidents since 1984 and will /(C) celebrate his 80th birthday on Christmas Eve. /(D) No error /(E)