In Health Canada's Listing of Monographs,why Does the Monograph for Beta-Carotene

In Health Canada's Listing of monographs,why does the monograph for beta-carotene contain a warning for smokers to consult a physician before using the supplement?

A) In rare cases,beta-carotene interacts with lung tissue to cause asthma.
B) Smokers are more likely to develop orange-coloured skin from the supplement.
C) Beta-carotene may increase the risk of lung cancer in smokers.
D) Beta-carotene may decrease the risk of lung cancer but it must be taken in combination with vitamin E.