Agree or Disagree?

[mahrousahmed]

In our mid-term exam January 2016, the examiner copied these two following sentences from an outside cook book. She \ He asked the students to choice the correct answer:

1) I ..........to a party tomorrow, would you like to come?
a) am going b)will go c) goes d) will have gone

the examiner's answer was 'am going'
I politely objected and debated that the answer should be "will go" as the sentence here doesn't have a plan or an intention or even arrangement as the speaker says,"....a party......" not ".........the party ........"
What's your opinions my dear colleagues?