Denny : Mr. Hendra, I`d like you to come to my birthday party next Sunday.
Mr. Hendra : That`s very kind of you, but I`m afraid I can`t. I have already made an appointment. Have a nice party.
The underlined sentence in the dialog above is.
An apology
a.An invitation
b.A large taking
c.A greeting
d.Agreement

someone can help me​