The most appropriate color combination for sun protection among the options provided is [B] White above and black below. White reflects sunlight, helping to keep the area beneath the umbrella cooler by deflecting heat. Black absorbs sunlight, effectively preventing it from passing through the umbrella, thus providing shade. This combination creates a balance between reflection and absorption, maximizing sun protection. Black underneath also reduces glare from below, enhancing visibility and comfort. Conversely, [A] Black above and white below might absorb more heat from the sun, potentially making the shaded area warmer. [C] Both black above and below could result in excessive heat absorption, making the shaded area uncomfortably warm. [D] Both white above and below lack the contrast needed for effective sun protection, potentially allowing more sunlight to pass through. Therefore, option [B] is the most suitable for sun protection.