How can we control/kill weeds like dandelions in a lawn without killing the grass?

a. Only natural organic oils and vinegars can control weeds in a lawn, not synthetic herbicides.
b. Some herbicides are selective for broadleaf plants and work by disrupting the fine balance of biochemical processes that occur in these weeds.
c. It is not possible to selectively control weeds in a lawn
d. Herbicides are used when the weeds are actively growing but the grass is still dormant.