Read the following passage and mark A, B, C, or D to indicate the correct answer to each of the blanks.

Located in central Africa, Lake Victoria is a very unusual lake. ___(1)___ of the largest lakes in the world; it is also one of the youngest. Estimated to be about 15,000 years old, it is a relative baby compared with Earth’s other very large lakes, ___(2)___ more than two million years old. Yet judging by the variety of life in it, Lake Victoria ___(3)___ a much older body of water. Usually, lakes need a much longer time ___(4)___ by a diverse array of life-forms. It is common for new lakes to contain only a small number of species. Lake Victoria, however, is packed with colorful fish, most notably, cichlids. There are ___(5)___ 500 different species of just this one type of fish.