which preposition is proper?

[sahel4]

The party is ____ next week.
it is one of tests in this site but i could nt find correct answer.

 

[sahel4]

Quiz: Prepositions of Time- In On At :


Q12 - The party is ____ next week.
in
on
at
---
(quiz from this site)

 

[bhaisahab]

Quiz: Prepositions of Time- In On At :


Q12 - The party is ____ next week.
in
on
at
---
(quiz from this site)

No preposition is necessary, a context for "on" is possible "The party is on", in other words "The party is going to take place".