‘I had just sat down to eat my supper when I heard someone knocking at the door’. This phrase could be correctly substituted by: At the time I sa...

‘I had just sat down to eat my supper when I heard someone knocking at the door’. This phrase could be correctly substituted by:

At the time I sat down to eat my supper than I heard someone knocking at the door.

When I sat down to eat my supper than I heard someone knocking at the door.

No sooner had I sat down to eat my supper than I heard someone knocking at the door.

Before I sat down to eat my supper, I heard someone knocking at the door.