An immersion electric boiler can have capacity as high as ___________ kW.

An immersion electric boiler can indeed have a capacity that can reach up to 30,000 kW. This high capacity is due to the design and functionality of immersion heaters, which utilize electric resistance heating elements that are immersed directly in the water being heated.

Immersion electric boilers are widely used for their efficiency and ability to offer significant heat output for various applications, such as heating water in commercial and industrial settings. The high wattage rating allows these boilers to quickly and effectively heat large volumes of water, catering to the demands of larger systems.

While the lower choices reflect capacities for smaller or standard appliances, the correct answer aligns with the maximum potential output of immersion electric boilers, illustrating their capability in high-demand scenarios.