In the following passage, some words have been deleted. Read the passage carefully and select the most appropriate option to fill in each blank.
Can we see (1) _________ the earth is a globe? Yes, we can, when we watch a ship that sails out to sea. If we watch closely, we see that the ship begins (2) _________. The bottom of the ship disappears first, and then the ship seems to sink lower and lower, (3) _________ we can only see the top of the ship, and then we see nothing at all. What is hiding the ship from us? It is the earth. Stick a pin most of the way into an orange, and (4) _________ turn the orange away from you. You will see the pin disappear, (5) _________ a ship does on the earth.

Select the most appropriate option to fill in blank number 1.

1. A
   where
2. B
   that
3. C
   if
4. D
   whether