In LAN Utilization U= 100 * (F/R) / (F/R + T*C)
where , U= Percentage of Utilization
R = Transmission Rate
F = Number of bits in a frame
T = Slot Time
C = Number of Contention Intervals = (1-1/N)1-N - 1
N = Number stations
Frame size = (512 *8 ) bits = 4096 bits
Data rate is 10 Mbps
F/R = 4096 bits/10 Mbps = 409.6 µsec
Number of stations, N = 500
But here C=No of Contentions given is= 1.7
U = (100 * 409.6) / ( 409.6 + 51.2* 1.7)
= 40960 / (409.6 + 87.04)
= 40960 / 496.64
= 82.4
Hence, channel utilization is 82%.
So Option B is the answer
for references: https://gateoverflow.in/96567/ethernet