1. The admission of Missouri as a slave state was controversial in the Senate because...

A. The senate was pro-slavery
B. It would create sectionalism***
C. It would upset the balance
D. The senate was anti-slavery

No.

It's C :)

To answer this question, we can start by understanding the context of the admission of Missouri as a slave state.

First, it is important to note that during the time period in question (early 19th century), the issue of slavery was a significant and deeply divisive topic in the United States. The country was divided between Northern states, which were generally against slavery, and Southern states, which heavily relied on slavery for their agricultural economy.

With this context in mind, let's look at the options provided:

A. The senate was pro-slavery: This option suggests that the senate's support for slavery was the reason for the controversy. However, it is important to remember that the senate was composed of representatives from both Northern and Southern states, and opinions regarding slavery varied widely among these representatives. Additionally, the controversy surrounding the admission of Missouri was not solely based on the ideological stance of the Senate.

B. It would create sectionalism: This option suggests that the admission of Missouri as a slave state would further deepen the divisions between the North and the South. This is the correct answer. The admission of a new slave state had serious implications for the balance of power in the Senate, as it would increase the number of representatives from pro-slavery states and potentially tip the balance in favor of the South.

C. It would upset the balance: This option reiterates a point made in the explanation for option B. The addition of a new slave state would indeed upset the balance between pro-slavery and anti-slavery states in the Senate. Therefore, this is also a valid answer choice.

D. The senate was anti-slavery: This option suggests that the Senate was opposed to slavery, which is not entirely true. While there were senators who were against slavery, there were also those who were pro-slavery or had mixed opinions on the issue.

In conclusion, the admission of Missouri as a slave state was controversial in the Senate primarily because it would create sectionalism and upset the balance between pro-slavery and anti-slavery states.