Under what condition is Toby's promise to pay his brother a portion of his commission legal?

The legality of Toby's promise to pay his brother a portion of his commission hinges on the relationship and involvement of parties in the real estate transaction. In this case, option B is correct because for a commission to be legally shared, the person receiving the commission must be actively involved in the transaction. If Bryant is a party to the transaction, this establishes a legal basis for him to receive part of Toby's commission.

This scenario aligns with the principle that commissions in real estate sales are often structured around contributions to the transaction, which must be recognized by law. Sharing a commission is typically permissible only if the person receiving it has a legitimate stake or involvement in the deal.

The other options highlight conditions that might not inherently grant the legal right to share commission. For instance, just being an employee of the brokerage or having a real estate license doesn't automatically entitle someone to a portion of another’s commission without their involvement in the transaction. A verbal agreement can be risky in real estate dealings as it leads to ambiguity and potential disputes, and legal agreements are generally preferred to enforce such arrangements.