Two Coffee-Vending Machines Are Studied to Determine Whether They Distribute $\mu$

Two coffee-vending machines are studied to determine whether they distribute the same amounts.Samples are taken and the number of ounces is recorded for each machine.
What is the appropriate null hypothesis for the claim that they distribute the same amount of coffee?

A) H₀: $\mu$ _DA $\ge$$\mu$ _DB
B) H₀: $\mu$ _DA = $\mu$ _DB
C) H₀: $\mu$ _DA $\le$ $\mu$ _DB
D) H₀: $\mu$ _DA $\neq$$\mu$ _DB