Which the maximum distance from the part for observation while visual testing?

a$)11\mathrm{.}8$ in

b$)23\mathrm{.}6$ in

c$)35\mathrm{.}4$ in

d$)47\mathrm{.}2$ in

If endoscopic device is to be used in VT control, which of the following does not have importance?

a$)$ Work time

b$)$ Material type

c$)$ Angle of vision