Task: Class Definition Understanding (ontology: Sciences/Biology)

Which of the following definitions best describes 'B axonemal microtubule'?

A. One of two microtubules present in the axonemal central pair. It is distinguishable from the C2 axonemal microtubule (also called C2 tubule) by the presence of differing protein components of the projections.
B. A complete microtubule with 13 protofilaments that fuses with an incomplete microtubule called B tubule (containing 10 protofilaments only) to form an axonemal outer doublet. Inner and outer dynein arms, as well as the radial spoke, are attached to the the concept.
C. An incomplete microtubule containing 10 protofilaments that fuses with a complete microtubule called A tubule (containing 13 protofilaments) to form an axonemal outer doublet.
D. One of two microtubules present in the axonemal central pair. It is distinguishable from the C1 axonemal microtubule (also called C1 tubule) by the presence of differing protein components of the projections.

Answer: An incomplete microtubule containing 10 protofilaments that fuses with a complete microtubule called A tubule (containing 13 protofilaments) to form an axonemal outer doublet.