Which of the following describes a relationship of commensalism?

a. oxpecker birds eat parasitic ticks off the backs of zebras

b. the tapeworm latches itself in the intestines of a rat feeding off all the nutrients eaten by the rat

c. a polar bear catches a seal for dinner

d. birds feed off the insects that are stirred up from the grasses as cattle move through

i won't lie i don't know so go online and ask google thats what i do

the peaceful equids (horses, donkeys and zebras) were enslaved by the human race to do our bidding -- sorry, domesticated -- several thousand years ago, and since that time they've been an invaluable resource for transportation, agriculture, warfare, companionship and sometimes-horrifying entertainment.