The common ancestor to snails, insects and vertebrates lived approximately ________ years ago.

The common ancestor to snails, insects and vertebrates lived approximately ________ years ago.
 
  a. 85 million
 b. 275 million
 c. 500 million
 d. 110 million
 e. 400 million

Question 2

I've cloned a genomic library and know that my bacteria have foreign DNA fragments inserted into the
  cloning vector. I now need to identify the specific bacteria that have the gene coding for protein X.
  How can I locate these bacteria?
 
  a. DNA hybridization of the different colonies
  b. PCR of the same bacterial mixture that was spread on agarose plates
  c. restriction endonuclease treatment of DNA from some of the bacterial colonies
  d. agarose gel electrophoresis of DNA isolated from the bacterial colonies
  e. transfer the bacterial colonies to filter paper