Most tv shows depend on ad funding and would be canceled without it. NO ad $$ > no show However, advertisers will not pay for commercial air time unless many people watching the show buy the advertised products as a result. ad $$ - > many buy products NOT many buy products - > NO ad $$ Therefore, if people fail to buy products advertised, these shows will soon be canceled. NOT many buy products - > no show Thus, anyone who feels a TV show is worth preserving ought to buy the products advertised.
The difference between (A) & (B) is subtle but it is in the emphasis on individual v. collective action. (A) says that "if one feels.." "unless one took certain actions" "then one ought to take those action" versus (B) says "unless many people took certain actions...". The argument tells us that ad revenue requires that MANY people watching the show buy the products, meaning an action of one person or even a few people cannot prevent the show from being canceled. It requires "many people" as (B) correctly points out.