20X Objective Becke Line Dispersion Staining

These are 5 micrometer glass fibers that have a refractive index of 1.550. A: 1.545 Cargile High Dispersion Liquid. B: 1.550 Cargile High Dispersion Liquid. C: 1.555 Cargile High Dispersion Liquid. D: 1.560 Cargile High Dispersion Liquid.