D? I'm aware that I'm late
Sorry but the answer may be right
This is true, this isn't a question, it's a fact.
Answer:
A toilet requires a large amount of cold water to flush. So, when the toilet flushes while you're in the shower, it's stealing from your shower's cold water supply. When the pressure-balancing valve senses the drop in cold water pressure, it responds by restricting the hot water pressure.
