By a contract there are two sets of promises, with one set of promises being legal, and other set of promises being illegal. In view of the statement, which one of the following is correct?

There can be such a contract vide Section 23 of the Indian Contract Act

The contract as a whole will be enforceable at the option of the buyer and not the seller

There can be a contract of two set of promises, with one set of promises being legal and the other set of promises being illegal, provided both the set of promises are a commercial contract and the monetary value of the illegal set of promises is reduced from the value of the legal set of promises, and enforcement is only for the net value