Task: Class Definition Understanding (ontology: Earth_Environment/SWEET)

Which of the following definitions best describes 'bow shock'?

A. The the concept is a discontinuity that forms in the solar wind when the supersonic solar wind encounters the magnetic field of a planet, very similar to the shock wave that forms upstream of an aircraft moving at a supersonic speed.
B. The fault-parallel displacement is effectively zero, as in an extraction fault.
C. A chemical the concept is a pure chemical substance consisting of two or more different chemical elements[1][2][3] that can be separated into simpler substances by chemical reactions[4] and that have a unique and defined chemical structure. Chemical compounds consist of a fixed ratio of atoms[3] that are hold together in a defined spatial arrangement by chemical bonds. [Wikipedia]
D. An eruption column of hot volcanic ash and gas emitted into the atmosphere during an explosive volcanic eruption. [Wikipedia]

Answer: The the concept is a discontinuity that forms in the solar wind when the supersonic solar wind encounters the magnetic field of a planet, very similar to the shock wave that forms upstream of an aircraft moving at a supersonic speed.