Read the following announcement and mark the letter A, B, C, or D on your answer sheet to indicate the correct option that best fits each of the numbered blanks from 13 to 16.

GREAT BARRIER REEF TOUR, AUSTRALIA

* Dive with us to (13) ______ the most beautiful coral reef in the world

* Swim in (14) ______ with colourful fish

* Watch 3D documentaries (15) ______ about sea animals and the coral reef, and what you can do to (16) ______ it

* Price: Only $99/adult & $59/child

* Time: 9 a.m. - 5 p.m. every day

Question 15.