Choose the correct singular nouns.

The correct answers for each question are: 1 - E (4, 5, 6), 2 - E (2, 4, 5), 3 - A (2, 5, 6), 4 - D (1, 3, 5), 5 - B (1, 4, 6), 6 - B (2, 4, 5), 7 - D (2, 3, 6), 8 - C (1, 3, 5), 9 - C (3, 4, 5), 10 - E (3, 4, 6), 11 - C (3, 4, 5), 12 - D (2, 3, 4), 13 - A (1, 3, 5), 14 - C (2, 3, 6), 15 - D (4, 5, 6), 16 - A (3, 4, 6).