A. Snap-on ferrite chokes
B. Low-pass and high-pass filters
C. Band-reject and band-pass filters
D. All of these choices are correct
We use ferrite chokes for both bringing down the general received interference level and preventing RFI on our consumer grade electronics. We have installed ferrites throughout our house on our phone lines, power cables, and cable TV coaxial cables. Look for type for type 31 and 43 ferrites at hamfests.
We also have low-pass filters installed between the antenna and our shortwave receiver.