Although the Government allowed Nestle to export Maggi,

Although the Government allowed Nestle to export Maggi, there was no word on the domestic ban....

1. which the government had clamped earlier
2. which the government has clamped earlier
3. which the government could clamped earlier
4. which the government should clamp earlier

Past perfect form of the verb has to be used to indicate that the ban clamped prior to the permission to export Maggi.