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Nilanjan Bhowmick AIR 3, CSIR NET (Earth Science)
Saurabh 1
Actually Lehmann discontinuity is probably renowned for increment ( abrupt increment would be more apt ) in the body waves velocities or seismic wave velocities(usually P and S wave, found dominating in the subsurface or at the depth of 220km. There is basically a percentage increase of 3-4% in the seismic wave velocities( P and S wave velocity). Actually this discontinuity was discovered in the vicinity of upper mantle by using short period body waves (preferably of ~0.25Hz) at some depth of around 200-220km. So correct option is (B).