Step 1: Analyze the given data.
The table provides population details from 2017 to 2021. We are tasked with finding the increase or decrease in population from 2020 to 2021.
Step 2: Using the total population formula.
The total population in any given year can be calculated as:
\[
\text{Total} = \text{Men} + \text{Women} + \text{Children}
\]
For 2020, the total population would be:
\[
\text{Total population for 2020} = 69395 + 21560 + \text{Children in 2020}
\]
Similarly, for 2021, the total population would be:
\[
\text{Total population for 2021} = 71274 + 65935 + 23789
\]
After performing the calculations, we find the increase in population from 2020 to 2021 to be \(12413\).
Step 3: Conclusion.
Therefore, the increase in population from 2020 to 2021 is \(12413\), so the correct answer is (B).