3. Read the following paragraph; then choose the correct answers.

(1) Phosphates pollute our water. (2) Phosphates become highly concentrated in rivers and lakes. (3) They are common in detergents and fertilizers. (4) Algae populations thrive in phosphates and grow rapidly. (5) The population may become so large that it uses up all the other available nutrients necessary to life. (6) Algae consume large amounts of oxygen. (7) Less oxygen is available for other aquatic organisms. (8) Algae can also block sunlight to other living creatures in a body of water. (9) Life may be eliminated, resulting in a stagnant body of water.

What transitional word or phrase best fits at the beginning of sentence 9?

In the end,
On the other hand,
Of course,
For example,
On the contrary,