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

Which of the following definitions best describes 'cirrus uncinus cloud'?

A. A cirrus cloud which 1) is structurally organised in patches, 2) is sufficiently dense to appear greyish when viewed towards the local star and 3) may veil, the local star, obscure its outline, or even hide it entirely.
B. A cirrus cloud which occurs as a detached unit or a thin veil and consists of nearly straight or irregularly curved filaments that do not terminate in hooks or tufts.
C. A cloud which is cirriform and is formed by condensation events centred on an aircraft's contrail.
D. A cirrus cloud which does not have grey parts and which is often shaped like a comma, terminating at its highest point in a hook, or in a tuft, the upper part of which is not in the form of a rounded protuberance.

Answer: A cirrus cloud which does not have grey parts and which is often shaped like a comma, terminating at its highest point in a hook, or in a tuft, the upper part of which is not in the form of a rounded protuberance.