We believe that this was an easy question. statement 5 " the retention of plastic particles in the gut" and "Aside from clogging up the digestive tracts" in statement 3 can be connected together. Thus 53 form a pair. 1 must come before 53 because it talks about marine animals eating the plastic. So we have 153 in sequence. 4 introduces the idea by talking about plastic and the environmental problem it brings with itself. So we have 4153 in sequence, with option 2 becoming the odd one out.