Explanation:

The options given are:
1. fruits[0]
2. fruits[1]
3. fruits[-1]
4. fruits[3]

Option 4: fruits[3]
This option does not contain the proper use of index numbers.

Explanation:
In programming, index numbers are used to access elements in a list or an array. The index numbers start from 0 for the first element and increment by 1 for each subsequent element. Therefore, to access the first element of a list, we use the index number 0.

Problem with Option 4:
The list "fruits" is not defined, so we cannot determine the index number 3. If the list contains fewer than 4 elements, accessing index number 3 would result in an "IndexError" because it is out of range.

Example:
Let's consider an example where the list "fruits" contains only 3 elements: ["apple", "banana", "orange"].

- fruits[0] would return "apple" because we are accessing the first element of the list.
- fruits[1] would return "banana" because we are accessing the second element of the list.
- fruits[-1] would return "orange" because negative index numbers are used to access elements from the end of the list. -1 represents the last element, -2 represents the second-to-last element, and so on.

However, if we try to access fruits[3], it would result in an "IndexError" because the list only contains 3 elements and the index number 3 is out of range.

Conclusion:
Option 4 does not contain the proper use of index numbers because it attempts to access an element at an index that may be out of range.