Final answer:
There are 9999 natural numbers that have no more than 4 digits.
Step-by-step explanation:
To determine the number of natural numbers that have no more than 4 digits, we can observe that the largest 4-digit natural number is 9999. Therefore, we need to count the number of natural numbers starting from 1 up to 9999.
To do this, we subtract 1 from 9999 to exclude the number 0, and then add 1 since we need to include the number 9999. This gives us a total of 9999 - 1 + 1 = 9999 natural numbers.
So the correct answer is a. 9999.