The correct option is D accomplices
Option D: The word 'accomplice' refers to a person who helps another person in committing a crime.
In the given sentence, the words 'gang', 'convicted' both refer to a crime that has been committed, for which the gang has been declared guilty. Hence the word is used for the gang members (other than the gang leader) and option D is correct.
Option A: 'Colleagues' is a person with whom one works in an office or professional establishment. Being in a gang and committing crimes is not a business; hence this word isn't relevant here and option A is incorrect.
Options B and C: 'Disciple' refers to a person who follows a spiritual leader or the likes. Similarly, 'student' refers to a person studying in an educational institution. These words do not relate to the members of a gang. Hence B and C are incorrect.