Under the conditions when the depth of water is too much, to make a continuous record of the depth of water below a boat or ship, the instrument generally used is

Under the conditions when the depth of water is too much, to make a co

1.	Under the conditions when the depth of water is too much, to make a continuous record of the depth of water below a boat or ship, the instrument generally used is
A.	sound box
B.	fathometer
C.	d B meter
D.	None of the above
E.	Any of the above
Answer» C.