Alack of vitamin d is said to be detrimental to the maintenance of bone density. if a
scientist wanted to determine whether this view was supported by scientific evidence,
which of the following would be the best method of doing so?
(a) carry out a survey of people with normal bone density to find out whether they
take vitamin d tablets or not
(b) compare the bone density of two groups of people with low bone density after
providing only one of the groups with vitamin d
(c) compare the incidence of people with low bone density in two different populations
(d) carry out an experiment in which a group of people with normal bone density are
exposed to very little sunlight to prevent the production of vitamin d