The sentences that contain an example of contested usage are:
C. • The chair for the chair of the board of directors is at the head of the board table. D. • The postman needs to know who this letter is addressed to so it can be delivered.
Explanation:
- In sentence C, the term "chair" can contest the traditional use of "chairman" or "chairperson," leading to discussions about the appropriate terminology.
- In sentence D, the phrase "who this letter is addressed to" uses informal grammar, as traditionally it should end with "to whom this letter is addressed," leading to a contested usage in terms of formal vs. informal English.