#30=C, This is because resistance in Parallel is always lower then series, this means it has to be be either C or D, however D contains a resistor so its not D and hence it has to be C.
#30=D, this is because electrons go from - to + thus if D is broken electrons will not flow to the other lamps.
#34=C, using Flemings grip rule for this one, you will find the current, and thus the direction of the Magnetic field
#37=A, Anode is always positive(this is to sharpen the image or make it more clear) remember the cathode emits NEGATIVE electrons thus the top Y plate has to be positive for it to move upwards.
Hope it helps Moonlyte