The original sentence is: "Although I don't usually like parties, I (said I would go) 16. , as I hadn't been to one in ages."

The original sentence is: "Although I don't usually like parties, I (said I would go) 16. _____, as I hadn't been to one in ages."

The phrase "said I would go" indicates that the speaker accepted the invitation. We need to choose the most precise reporting verb from the given options.

• A. agreed: To consent to something or to say yes. This fits the context of accepting an invitation.
• B. confirmed: To state or show that something is definitely true or correct, or to make an arrangement or meeting certain. While one might confirm attendance, "agreed" is a more direct replacement for the initial acceptance.
• C. admitted: To confess to be true or to acknowledge, often implying reluctance or revealing something previously hidden. This does not fit the context of accepting an invitation.
• D. surrendered: To give up or yield. This is completely inappropriate for accepting an invitation.

"Agreed" is the most suitable and precise verb to replace "said I would go" in this context, as it directly conveys the acceptance of the invitation.

The completed sentence would be: "Although I don't usually like parties, I agreed, as I hadn't been to one in ages."

The correct option is A.