Complete the Number Sequence: 20,000, 20,001, 20,002...

To solve this problem, we will continue the sequence $20,000, 20,001, 20,002, \ldots$ by adding 1 to the last number provided.

• Start with the last number in the sequence, which is $20,002$.
• Step 1: Add 1 to $20,002$ to get $20,003$.
• Step 2: Add 1 to $20,003$ to get $20,004$.
• Step 3: Add 1 to $20,004$ to get $20,005$.

Thus, the continuation of the sequence is $20,003, 20,004, 20,005$.

Therefore, the correct answer is choice 1: $20,003,20,004,20,005$.