The lymph not only acts as an immune system, but also helps in circulatory retrieval of small amounts of escaped fluid from capillary diffusion due to pressure alterations. if these lymph vessels become occluded, flow of fluid will become backed up and will result in gross edema(swelling) of the affected area. With the continual inability to retrieve fluid, less and less fluid returns to the heart resulting in a sort of hypovolemic state. however this is highly unlikely and is usually caught before it is allowed to become this severe.
If you believe there has been a heatstroke, you would call 911 immediately. You then should move the person out of the heat, remove excess clothing, and cool the person in any way possible, such as a cool bath or shower.
In general, for most things, A would be correct (Any time of the day). It kind of depends on what you ar collecting the sample for. I think the earlier the better but it doesnt usually matter.
