Please answer a question about the following article about Incandescent light bulb:

Objections to banning the use of incandescent light bulbs include the higher initial cost of alternatives and lower quality of light of fluorescent lamps. Some people have concerns about the health effects of fluorescent lamps. However, even though they contain mercury, the environmental performance of CFLs is much better than that of light bulbs, mostly because they consume much less energy and therefore strongly reduce the environmental impact of power production. LED lamps are even more efficient, and are free of mercury. They are regarded as the best solution in terms of cost effectiveness and robustness.

Which type of light bulbs is considered most cost effective and robust?
LED lamps
The second paragraph states: "LED lamps are even more efficient, and are free of mercury. They are regarded as the best solution in terms of cost effectiveness and robustness."
Therefore, LED lamps is considered most cost effective and robust.