Which of the following is correct about hydroplaning?

It does not take a lot of water to cause hydroplaning. Hydroplaning can occur at speeds as low as 30 mph if there is a lot of water. Hydroplaning is more likely if tire pressure is low, or tread is worn. (The grooves in a tire carry away the water: if the grooves are not deep, they do not work well.) [California Commercial Driver Handbook]