Is there any way to reduce the carcinogenicity/toxicity of a substance?

There exist different types of cancer, some of which have a remedy to be treated and some of which may never have in the near future. Technologies have advanced, the field of Science and biomedical sector have witnessed significant improvements in the previous decades. Many cancers which seemed impossible to be treated years ago have today a reliable cure. So it depends on which type of cancer and which stage of cancer are you specifically talking about.

Yes. Indeed there are various scientists who are trained to prepare and handle these carcinogens safely in a laboratory. These carcinogens are used to prepare various useful substances such as drugs and medicines so their usage needs to be monitored regularly and handled carefully. The production must comply with legal rules and standards.

In this carbocation +M effect of -OCH₃ group stabilizes the carbocation.

While in option (A) and (B), +M of -OCH₃ will not work but in option (C), +M of -OCH₃ works so due to more delocalization in option (D), it is more stable.