$15$

You have a $10$ Mbps half$-$duplex Ethernet network that uses two communication cable segments. In one cable of length $11,$ the signal speed is $v1={2\mathrm{.}5}^{**}{10}^{{?}^{{?}^{?}}}8\frac{m}{s}.$ In the second part of the network, the signal speed is v$2={2\mathrm{.}0}^{**}{10}^{{?}^{{?}^{?}}}8\frac{m}{s}.$ What is the allowable length of the second fragment to detect all collisions? There is no signal attenuation. ${}_{40}(10$ Puan$)$

A

B $($Only need answer$)$