To solve this question, the user needs to know about equivalence classes and boundary testing. Equivalence partitioning is a software testing technique that divides the input data of a software unit into different partitions of valid and invalid data. The purpose of this is to reduce the number of test cases needed to test the software while increasing the effectiveness of the tests. Boundary testing is a software testing technique that checks whether the input data to a software system is at its minimum or maximum limits.

In this question, the valid equivalence classes are numbers between 10000 and 99999 inclusive. The valid boundaries are 10000 and 99999.

Let's go through each option and see which inputs are a result of designing tests for only valid equivalence classes and valid boundaries:

A. 1000, 5000, 99999: Option A includes invalid equivalence classes and is not a result of designing tests for only valid equivalence classes.

B. 9999, 50000, 100000: Option B includes an invalid boundary (100000) and is not a result of designing tests for only valid boundaries.

C. 10000, 50000, 99999: Option C includes valid equivalence classes and valid boundaries. It includes the minimum and maximum values of the valid equivalence classes.

D. 10000, 99999: Option D includes valid boundaries but only one valid equivalence class. It does not include other valid equivalence classes between 10000 and 99999.

E. 9999, 10000, 50000, 99999, 10000: Option E includes invalid equivalence classes (9999 and 10000) and duplicate input (10000). It is not a result of designing tests for only valid equivalence classes and valid boundaries.

Therefore, the correct answer is:

The Answer is: C