4. What is a common feature of both active and passive immunity? A They are acquired by vaccination. B They are always short-tem. C They involve the activity of memory cells. D They involve antibodies.

In cattle a single gene with two alleles determines fur color the fur can be red white or roan roan fur has both red and white hair which of the following statements is true a the allele for roan fur color is dominant over red and white fur color b the allele for red fur color is dominant over white and roan fur color c the roan and white alleles are expressed independently of the other d the red and white alleles are expressed independently of each other