ans is B 143 ms and 123 ms
at clock time 160 millisecond only request number 1 2 3 4 are there to be serviced
request number 5 (with track no 75) will be ready after 15 millisecond
starting head position 65
now for SSTF 12 40 75 85 100
it will serve 85(since 75 is not come yet) first then 75 then 100 then 40 and finally 12
so total movements =20+10+25+60+28=143 total time 143x1 ms=143ms
now for look 12 40 75 85 100 direction towards highest no of tracks
it will serve 85(since 75 is not come yet) first then 100 then 75 then 40 and finally 12
so total movements =20+15+25+35+28=123 total time 123x1 ms=123ms