In an experiment, which type of variable does a researcher have control over and wish to manipulate?

Hank bought a farm that had an old barn. He noticed one day that the roof of the barn was swaying in the wind. Hank went to see his insurance agent and he insured the barn for $20,000

The agent didn't ask if the roof might collapse, and Hank didn't say anything about it. One week later there was a strong wind and the roof collapsed. Assuming the insurer can prove it, under what legal grounds could the insurer deny payment of the claim? A) estoppel B) concealment C) warranty D) misrepresentation

To create a 1:1 relationship between two tables in Microsoft Access:

A) the Indexed property of the foreign key column must be set to No. B) the Indexed property of the foreign key column must be set to Yes (Duplicates OK). C) the Indexed property of the foreign key column must be set to Yes (No Duplicates). D) the Data Type of the foreign key column must be set to AutoNumber. E) the Smart Tag property of the foreign key column must be set to Foreign Key.