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

[EX Q]: What does every plane have?, Context: Grey-box testing (American spelling: gray-box testing) involves having knowledge of internal data structures and algorithms for purposes of designing tests, while executing those tests at the user, or black-box level. The tester is not required to have full access to the software's source code.[not in citation given] Manipulating input data and formatting output do not qualify as grey-box, because the input and output are clearly outside of the "black box" that we are calling the system under test. This distinction is particularly important when conducting integration testing between two modules of code written by two different developers, where only the interfaces are exposed for test.
[EX A]: black box

[EX Q]: Who can remove the plague?, Context: A number of non-Greek etymologies have been suggested for the name, The Hittite form Apaliunas (dx-ap-pa-li-u-na-aš) is attested in the Manapa-Tarhunta letter, perhaps related to Hurrian (and certainly the Etruscan) Aplu, a god of plague, in turn likely from Akkadian Aplu Enlil meaning simply "the son of Enlil", a title that was given to the god Nergal, who was linked to Shamash, Babylonian god of the sun. The role of Apollo as god of plague is evident in the invocation of Apollo Smintheus ("mouse Apollo") by Chryses, the Trojan priest of Apollo, with the purpose of sending a plague against the Greeks (the reasoning behind a god of the plague becoming a god of healing is of course apotropaic, meaning that the god responsible for bringing the plague must be appeased in order to remove the plague).
[EX A]: god of plague

[EX Q]: In the operation of filaments, lower molecular weight gas does what better than higher molecular weight gas?, Context: While inert gas reduces filament evaporation, it also conducts heat from the filament, thereby cooling the filament and reducing efficiency. At constant pressure and temperature, the thermal conductivity of a gas depends upon the molecular weight of the gas and the cross sectional area of the gas molecules. Higher molecular weight gasses have lower thermal conductivity, because both the molecular weight is higher and also the cross sectional area is higher. Xenon gas improves efficiency because of its high molecular weight, but is also more expensive, so its use is limited to smaller lamps.
[EX A]:
conducts heat from the filament