Which of the following is true for an auction with reserve?

Goods cannot be withdrawn from sale after the offer has been made.
      
The seller retains the right to refuse the highest bidder.
      
Invitations to make an offer are not allowed.
      
A bid once made cannot be withdrawn and is legally binding.

Which of the following is used to resolve a case where the obligee fraudulently makes successive assignments of the same right to several assignees?
      
the English rule
      
an approval clause
      
anti-assignment clause
      
novation agreement

Which of the following phrases describes the term covenant?
      
an unconditional promise to perform
      
mutual rescission of a contract
      
a breach of contract
      
successive assignments of a right