Which of the following conclusions is supported by the data in this table?

A. African American representation in government has decreased.
B. More African Americans became registered to vote in Southern states.
C. White opposition to African American voting remains strong.
D. In all states, the percentage of African American voters is still less than the percentage of white voters.

\begin{tabular}{|c|c|c|c|c|}
\hline & \multicolumn{2}{|c|}{March 1805} & \multicolumn{2}{|c|}{November 2010} \\
\hline & \text{African American} & \text{White} & \text{African American} & \text{White} \\
\hline Alabama & 19.3 & 69.2 & 69.0 & 61.7 \\
\hline Georgia & 27.4 & 62.6 & 63.5 & 62.1 \\
\hline Louisiana & 31.6 & 80.5 & 75.8 & 74.9 \\
\hline Mississippi & 6.7 & 69.9 & 74.1 & 74.1 \\
\hline South Carolina & 37.3 & 75.7 & 68.6 & 69.7 \\
\hline
\end{tabular}

To determine which conclusion is supported by the data in the table, we need to analyze the information provided for African American and white voter percentages from March 1805 to November 2010 for the states listed. Let's examine the data step-by-step.

Given the data:

March 1805:
- Alabama: African American: 19.3%, White: 69.2%
- Georgia: African American: 27.4%, White: 62.6%
- Louisiana: African American: 31.6%, White: 80.5%
- Mississippi: African American: 6.7%, White: 69.9%
- South Carolina: African American: 37.3%, White: 75.7%

November 2010:
- Alabama: African American: 69.0%, White: 61.7%
- Georgia: African American: 63.5%, White: 62.1%
- Louisiana: African American: 75.8%, White: 74.9%
- Mississippi: African American: 74.1%, White: 74.1%
- South Carolina: African American: 68.6%, White: 69.7%

Differences in voter percentages:
- Alabama: Increase of 49.7% (from 19.3% to 69.0%)
- Georgia: Increase of 36.1% (from 27.4% to 63.5%)
- Louisiana: Increase of 44.2% (from 31.6% to 75.8%)
- Mississippi: Increase of 67.4% (from 6.7% to 74.1%)
- South Carolina: Increase of 31.3% (from 37.3% to 68.6%)

From the differences calculated, it's clear that the percentage of African American voters increased in all the states listed:

1. Alabama increased by 49.7%
2. Georgia increased by 36.1%
3. Louisiana increased by 44.2%
4. Mississippi increased by 67.4%
5. South Carolina increased by 31.3%

Therefore, the conclusion that is supported by the data is "More African Americans became registered to vote in Southern states."

This conclusion is evident as there is a positive increase in the percentage of African American voters in all the given states, showing a significant rise in voter registration among African American communities between March 1805 and November 2010.