The correct answer is: C. Fiber birefringence.
Birefringence is the optical property of a material having a refractive index that depends on the polarization and propagation direction of light. In fiber optics, birefringence is the difference in refractive indices of two orthogonally polarized modes propagating in an optical fiber.
Polarization is the property of a wave that has a definite orientation of its electric field vector. In optics, polarization is the property of light waves that have a definite orientation of their electric field vectors.
Cutoff is the minimum value of input power required to maintain a stable optical pulse in a fiber optic amplifier.
Fiber splicing is the process of joining two optical fibers together to form a continuous length of fiber.