In liver cells, galactose is converted to glucose 6 -phosphate in a four-step process; it then enters glycolysis. People with the genetic disease galactosemia lack one or more of the enzymes necessary to convert galactose to glucose 6-phosphate; galactose instead is converted to undesirable molecules that damage various organs. This disease can be controlled by a careful diet. What food or foods are a major source of galactose in the diet?