Albert is a broker, and he represents Brent, who is a home o…

Albert is a broker, and he represents Brent, who is a home owner. Brent would like to sell his home.  Candy comes forward, as a potential buyer of Brent’s home.  Brent instructs Albert to sell Candy the home.  Albert, instead, decides to sell the home to David.  What duty has Albert breached?