You know you can look this up for yourself, right? Take each term, put it in your browser and you'll get a definition for each, from which you can choose the right answer.
Let's look at them, though. If the luminosity remains constant, then they cannot be intrinsically variable. Intrinsic means internal, and the luminosity would vary, not remain constant.
Dwarf novae are very dim and are not stars; they are gas clouds, so that's out.
Extrinsic variables..that's where we want to go. Extrinsic means that something outside of the star itself is causing it to vary its luminosity when seen from Earth. An example would be an eclipsing binary star, such as Sirius A and B. One pair of the binary is dimmer than the other, so when it passes in front of the brighter, larger star, it causes it to seem less bright from our point of view. Neither star is intrinsically changing its luminosity; it is a matter of a dimmer star eclipsing the brightness of a more massive, brighter star as the binaries orbit around each other. When the dimmer star is behind or beside the brighter one, the luminosity of the binary seems to increase when seen from Earth, and when it is in front, the luminosity appears to dim, but it is not because of a change in the actual luminosity of either star. It is an illusion caused by the alternating positions of two stars of unequal magnitude that causes the apparent change of luminosity.