Why Would Perfectly Competitive Industries Advertise Even Though Individual Firms

Why would perfectly competitive industries advertise even though individual firms do not?

A) Even though the output of an individual firm would be considered homogeneous to other firms,the industry output would be differentiated (for example,Florida orange juice versus imports) .
B) Individual perfectly competitive firms don't need to advertise because they already have market power,but the industry would need to advertise.
C) Government price supports exist for most perfectly competitive producers,so they don't need to advertise,but industry price supports don't generally exist.
D) Industries advertise because they pay for commercials and it allows consumers to watch TV and listen to the radio for "free."
E) Individual firms produce perfectly differentiated output,but the industry produces homogeneous output that needs to be differentiated.