I would say that for example an unethical tactic would be to promote the expanded use of hydrocarbons by expanding pipelines and tanker traffic which can result in oil spills on land and also in the precious oceans. Another unethical thing from the past was to promote the smoking of cigarettes by making it look 'cool' thus ignoring the potential damage to one's health from lung cancer.
There needs to be a comma at A because it is an appositive phrase. Meaning he is describing someone or something and that is separate from the sentence its self