Answer:
H - Formerly part of Mexico - best completes the diagram above.
The two descriptions listed in the diagram are related to territories in North America that were annexed by the United States at different times in history. The first territory was annexed in 1845 and settlers were attracted by free land. The second territory was ceded to the United States in 1848 and settlers were attracted by gold. Therefore, the missing piece of information that completes the diagram is that both territories were formerly part of Mexico. Option H is the only choice that accurately reflects this information. The other options are either irrelevant or do not fit the context of the diagram.