In this task, you are given a question and a context passage. You have to answer the question based on the given passage.

[Q]: Waves contain?, Context: As an electro-magnetic wave travels through the different parts of the antenna system (radio, feed line, antenna, free space) it may encounter differences in impedance (E/H, V/I, etc.). At each interface, depending on the impedance match, some fraction of the wave's energy will reflect back to the source, forming a standing wave in the feed line. The ratio of maximum power to minimum power in the wave can be measured and is called the standing wave ratio (SWR). A SWR of 1:1 is ideal. A SWR of 1.5:1 is considered to be marginally acceptable in low power applications where power loss is more critical, although an SWR as high as 6:1 may still be usable with the right equipment. Minimizing impedance differences at each interface (impedance matching) will reduce SWR and maximize power transfer through each part of the antenna system.
[A]: power


[Q]: What is Rayleigh scattering?, Context: In nature, the red color of blood comes from hemoglobin, the iron-containing protein found in the red blood cells of all vertebrates. The red color of the Grand Canyon and other geological features is caused by hematite or red ochre, both forms of iron oxide. It also causes the red color of the planet Mars. The red sky at sunset and sunrise is caused by an optical effect known as Rayleigh scattering, which, when the sun is low or below the horizon, increases the red-wavelength light that reaches the eye. The color of autumn leaves is caused by pigments called anthocyanins, which are produced towards the end of summer, when the green chlorophyll is no longer produced. One to two percent of the human population has red hair; the color is produced by high levels of the reddish pigment pheomelanin (which also accounts for the red color of the lips) and relatively low levels of the dark pigment eumelanin.
[A]: optical effect


[Q]: What can be found near sculptural ensembles?, Context: A number of sculptural ensembles of that era, erected at the tombs of royals and other dignitaries, have survived (in various degrees of preservation) in Nanjing's northeastern and eastern suburbs, primarily in Qixia and Jiangning District. Possibly the best preserved of them is the ensemble of the Tomb of Xiao Xiu (475–518), a brother of Emperor Wu of Liang. The period of division ended when the Sui Dynasty reunified China and almost destroyed the entire city, turning it into a small town.
[A]:
tombs of royals and other dignitaries


