berry, the seller, wants paul, the broker, to change from a single agency relationship to a transactional broker. paul agrees to do this as long as the transition disclosure is made in writing so that all parties understand what is happening. paul needs to transition to a transition broker when?

After the listing agreement is signed.
Only when the buyer requests that Paul, the broker, do so.
At any time during a transaction, as long as consent is given in writing.
At the closing.