why DoEs thE spEAkEr mEntion Air-ConDitioning
A．it's AnothEr possiBlE usE For sEAwAtEr.
B．it's nECEssAry For growing vEgEtABlEs in hot ClimAtEs.
C．it's usED to Cool wAtEr usED For irrigAtion.
D．it's thE primAry usE For ElECtriCity in thE unitED stAtEs.