In mercury arc rectifiers having grid, the arc can be struck between anode and cathode only when the grid attains a certain potential, this potential being known as

In mercury arc rectifiers having grid, the arc can be struck between a

1.	In mercury arc rectifiers having grid, the arc can be struck between anode and cathode only when the grid attains a certain potential, this potential being known as
A.	maximum grid voltage
B.	critical grid voltage
C.	any of the above
D.	none of the above
Answer» C. any of the above