Use whether. Transform the source sentence 'The board is deciding: should it renew the lease?' Rewrite the exact fragment 'should it renew the lease' as an embedded to-infinitive: The board is deciding ___ .
Correct answer
whether to renew the lease
Explanation
The unresolved choice is compressed into a to-infinitive, and that structure must be introduced by whether. If cannot stand directly before to renew in standard English.