The bacterium, E.coli, lives in the large intestines of mammals and feeds on undigested food ...

The bacterium, E.coli, lives in the large
  intestines of mammals and feeds on undigested
  food material. E.coli helps to synthesize
  vitamin K that is essential for mammalian
  blood clotting. The relationship between E.coli
  and mammals is a
 
  a. commensalism.
  b. mutualism.
  c. competition.
  d. predation.
  e. parasitism

Question 2

A hummingbird that pollinates morning glory
  flowers and nests in the crotch of an apple tree.
  The apple tree is not harmed or helped by the
  hummingbird. The relationship between the
  hummingbird and the apple tree is a
 
  a. mutualism.
  b. commensalism.
  c. competition.
  d. parasitism.
  e. predation