Call a positive integer monotonous if it is a one-digit number or its digits, when read from left to right, form either a strictly increasing or a strictly decreasing sequence. For example, 3, 23578, and 987620 are monotonous, but 88,7434 , and 23557 are not. How many monotonous positive integers are there?
Answer Choices
A. 1024
B. 1524
C. 1533
D. 1536
E. 2048