The ultrasound waves can penetrate into matter to a large extent because they have very high speed.
The ultrasound waves can penetrate into matter to a large extent because they have :
(a) very high speed (b) very high frequency (c) very high quality (d) very high amplitude.
Snakes are killed in large numbers because: (a) they are very poisonous (b) they kill rats (c) their skin is expensive (d) they damage the crops