Final answer:
The most useful feature of an almanac for planning a Fourth of July party would be the weather forecasts, as they provide essential information for outdoor event planning.
Step-by-step explanation:
If a person is trying to decide whether to throw a Fourth of July party over the summer, the most useful feature of an almanac would be D. Weather forecasts. This information can help the person plan for outdoor activities by providing details about the likelihood of rain, temperatures, and other weather conditions on that day. Knowing the weather in advance is critical for arranging outdoor events, such as barbecues and firework displays, which are common during Fourth of July celebrations.