For the purpose of calculating the minimum flow rate of a tankless type water heater, 'high−flow fixture' means a fixture with a flow rate of more than ___ gallons per minute, at ___ pounds per square inch, and a water velocity not exceeding ___ feet per second.
a) 2, 50, 6
b) 3, 60, 8
c) 4, 70, 10
d) 5, 80, 12