Negation, Kmart Barbells

If the statement “All sets of barbells in Kmart are on sale” is false, then which of the following statements must be true?

1. All sets of barbells in Kmart are not on sale.
2. There is some set of barbells in Kmart that is not on sale.
3. No set of barbells in Kmart is on sale.
4. Not all sets of barbells in Kmart are on sale.

1. II only
2. IV only
3. I and III only
4. II and IV only
5. I, II, and IV only

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