How to make buffalo chicken macaroni and cheese<br>Place the chicken breasts in a large saucepan and fill it with cold water. Add just enough water until the chicken is covered by an inch. Allow the water to boil on medium-high heat.
The chicken breasts are submerged under water
The context states to add an inch of water, but it doesn't say how big the breasts are... so we don't know if they are submerged (fully under) the water or not. The system likely assumed the level of water was not sufficient to cover a chicken breast. 
( z1 submerge :ARG1 ( z2 breast :part-of ( z3 chicken ) ) :ARG2 ( z4 water ) )