Answer:
B). A diaphragm and spermicide.
Step-by-step explanation:
As per the given description, the best-recommended method of contraception to the woman would be 'diaphragm and spermicide' as she is a chain smoker, has quite irregular menstrual cycles and requires a highly effective contraceptive. Thus, only the diaphragm along with spermicide would be a highly reliable source(as it is effective in almost of 90 plus percentage of the cases) for preventing pregnancy. Since she is a chain smoker, any kind of pill may invoke negative reactions and due to irregularity of periods, she can't even rely on them. Therefore, the diaphragm would help prevent the sperms from getting into the cervix and hence, option B is the correct answer.