Answer: Some members of Congress were upset when Nixon told them of his decision to resign.
Step-by-step explanation:
The detail that is included in the Washington Post article about Nixon's resignation but not in his resignation speech is that some members of Congress were upset when Nixon told them that he wanted to resign.
It should be noted that the intent of the resignation speech was so that President Nixon would be presented in the best possible way. On the other hand, the Washington Post article gave a a neutral view of President Nixon.
Therefore, the correct option is A.