For ethernet which follows CSMA / CD protocol , the following condition is necessary :
Transmission time = 2 * Propogation time (or) round trip time
Given round trip time = 46.4 micro sec
Transmission time = Data size / Data rate
So we have to find data size basically
So equating T.T = Round trip time
x / 10 * 106 = 46.4 / 106
==> x = 46.4 * 10
==> x = 464
Hence C) is the correct option.