Answer:
The correct option is: b) A diaphragm and spermicide
Step-by-step explanation:
Diaphragm is a type of birth control method that has been found to be moderately effective. The diaphragm has to be placed six hours before, over the cervix of the uterus with spermicide.
It is a barrier method of birth control, therefore, it does not interfere with the natural menstrual cycle of the female.
Therefore, for a 40 year old female who is a heavy smoker and has irregular menstrual cycles, a diaphragm with spermicide is the best recommendation.