Answer:
The correct option is C.
Explanation:
The two patterns are defined as follows:
- Pattern A starts at 20 and has the rule 'subtract 2'.
- Pattern B starts at 20 and has the rule 'subtract 1'.
Form the two patterns as follows:
Pattern A : 20, 18, 16, 14, 12, 10, 8, 6, 4, 2, 0
Pattern B : 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0
The first several terms of Patterns A and B are shown by:
Pattern A: 20, 18, 16, 14, 12, 10
Pattern B: 20, 19, 18, 17, 16, 15
Thus, the correct option is C.