Answer:
They should use "I" messages that clearly state how the speaker feels and what she wants.
Explanation:
Hedda and Kate are engaged in a conflict where they have to nag at each other to keep their dishes clean. When a person nags they use the "you message". This expresses to the listener and that they have to do the job they are being nagged about.
When an "I" message is being used then it makes the other person empathize with them. This makes them do the work in the interest of others. It also makes clear what a person feels because of the other's actions.
Hence, the "I" message should be used to resolve the conflict.