The association between low birth weight and maternal smoking during pregnancy can be studied by obtaining smoking histories of women at the time of their visit and then subsequently correlating birth weight with smoking histories.What type of study is this ?

The association between low birth weight and maternal smoking during p

1.	The association between low birth weight and maternal smoking during pregnancy can be studied by obtaining smoking histories of women at the time of their visit and then subsequently correlating birth weight with smoking histories.What type of study is this ?
A.	Clinical trial
B.	Cross sectional
C.	Prospective
D.	Case control
Answer» D. Case control