I'm confused as to why the answer isn't "or" instead of "and.". Since, while negating an 'and statement' you switch it to an 'or', how do you get to this correct answer? I can't figure it out.

Dyar, thanks for using the app. Negating an 'and statement' does not make it an 'or statement'. Where did you read about this rule?

1. When negated, the “and” connective switches to an “or”.
For example, the negation of “P + Q” is “~P or ~Q”.

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The above is from the introduction to the questions for this section. In this case, it seems that:

~(S + UR) -> D
~D -> S or UR

Where is the error here? It seems that, knowing that Fred and Barney are not disabled, all we can conclude is that The Flinstones could be silly and realistic, not silly and unrealistic, or both silly and unrealistic.

I would really appreciate help with this question!

I had the same question about this one as mentioned above....

Here's how I approach this. When you have an If A then B, you can conclude that If ~B then ~A.

In this case:
A= ~ (silly and unrealistic) -- no need to distribute the negation
B= disabled

Hence we can flip A and B while switching the signs:
If ~disabled, then ~[~(silly and unrealistic)]; the negations cancel each other in A, so:
If ~disabled, then (silly and unrealistic).

Since Fred and Barney are not disabled, then the FTV must be silly and unrealistic.