The correct option is
D 2m/sAveragevelocity=displacementtotaltimeweneedtofindouttheaveragevelocityforwholetimeintervalthatis10s.particlestartsfrom60min0secondsandreachto40min10secondsaftercoveringdistance50mand30min6minsecondsand4secondsrepectively.sonetdisplacementis60−40=20mtime=10saveragevelocity=2010=2m/sHence,
option (D) is correct answer.