Alex purchases a mountain bike from Vinny for $$4,000.$ Alex tells Vinny he'll Venmo him. Vinny owes Christina $$4,000$ so he assigns the right to collect the $$4,000$ from Alex to Christina. Before Alex pays, he realizes the bike is completely unusable, and he refuses to pay for the bike. Which of the following is true?

Question $31$ options:

The assignment of the $$4,000$ to Christina is subject to Alex's defenses to payment.

Alex has to pay Christina. It does not matter if Vinny breached their agreement.

Christina can enforce the assignment against Alex, but not Vinny.

All of the above.