The bands are listed in the question in their natural ascending order already — L, C, Ku, Ka — so the answer is 1, 2, 3, 4, option 1.

The nomenclature explains itself once the origin is known. The K band, from the German kurz meaning short, sits around 20 GHz — unfortunately right on the 22 GHz water-vapour absorption line. It was therefore split, and the two usable halves named for their position relative to it: Ku is K-under, below the absorption peak, and Ka is K-above. Remembering that one fact fixes their order permanently, since "under" must come first.

The engineering trade-off across the ladder. Moving up in frequency brings more available bandwidth — hence Ka band's use for high-throughput broadband — and allows smaller antennas for a given gain, since

\(G=\dfrac{4\pi A\eta}{\lambda^{2}}\)

and the gain rises as \(1/\lambda^{2}\). That is why a Ku-band domestic dish is 60 cm across while a C-band one is several metres.

What is given up is weather margin. Rain attenuation grows steeply with frequency: negligible at L band, a few tenths of a dB at C band, several dB at Ku, and severe at Ka, where heavy rain can close a link entirely. This is why C band remains preferred for tropical regions and for broadcast feeds that must never fail, and why Ka-band systems use adaptive coding and uplink power control to ride out fades.

Hence, the ascending order is 1, 2, 3, 4.