Kyle and Sheila work as preschool teachers. Which scenario is an example of gender discrimination?

Kyle has more experience as a preschool teacher and makes more money than Sheila.
Kyle is only asked to do manual labor tasks while Sheila is given all nurturing tasks.
Kyle makes the children's morning snack and Sheila makes the afternoon snack.
Kyle teaches the 3-year-old children and Sheila teaches the 4-year-old children.