If a pregnant woman becomes infected with rubella, a viral disease also known as German measles, the virus can adversely affect the formation of the baby's major organs, such as the heart. When would a rubella infection in a pregnant woman most affect a fetus? A. week 8
B. week 20
C. week 32
D. week 37

Week 20

Explanation:

It would affect most in the first 12 weeks.

relative dating involves things like higher layers are most recent than rocks lower in the sequence. this can be extended to the known sequence of fossils. rocks containing rabbit fossils are later than those containing dinosaur fossils.  

absolute dating methods mainly use radioactive elements that have known rates of decay and produce recognizable products. for example potassium 40 decays to produce argon. once a rock has solidified the argon is trapped. by measuring the argon and potassium0 you can get an accurate number for the age.  

some other methods are good for archaeological ages. dendrochronology involves recognizing the sequence of tree rings. the orientation of magnetized particles in baked clay can be used to date a fire.

hope this .. .