$29.$ Refractive index in a step index $\backslash ($ f $/$ o $\backslash )$ cable is

a$.$ the highest at core in graded index $\backslash (\backslash$mathrm$\{$f$\}/\backslash$mathrm$\{$o$\}\backslash )$

b$.$ the highest at border of the cladding surface

c$.$ the uniform for any place in the core

$30.$ Due to the feature that the whole process $-$

a$.$ mechanical splicing is relatively fast and easy and takes very short time.

b$.$ fusion splicing is normally used when time and professional skills are limite

c$.$ fusion splicing is relatively fast and easy and takes very short time.

$31.$ what type of connector is illustrated in the figure below?

a$.$ Butt type connector.

b$.$ Expanded beam connector.

c$.$ Splitter type connector.