Based on the information provided about the chart illustrating European support for the United States during the Revolutionary War, the conclusion that can be drawn is:
D. The US military lacked the funding and preparation necessary to achieve victory.
This conclusion is supported by the fact that while France provided various forms of support (naval support, weapons, supplies, and military training), Spain and the Netherlands primarily provided financial support. This suggests that the United States may not have been fully prepared or funded adequately for the war, leading them to seek assistance from these European allies.