hi , i think if you are 3 feet away with the condenser you won't have phase problems between the 2 mikes (assuming that all your wiring is right).

i would say : "listen" .

You won't hear any phase cancellation with headphones on - unless you sum to mono - because you won't hear the result of the sound waves at the relevant frequencies interfering with each other. A certain amount of cancellation will always occur with spaced mics. I hope I understood your question.

Definitely not choice B. A spaced pair wiill phase cancel but only at a frequency that is relative to the distance the mikes are from each other. Flipping the phase will put all the frequencies out of phase.
Choice a is the one to go, pan both mikes to the same point and listen. You can also try manually lining up the track that is 3 feet away with the close mic inside your daw after you record. This removes the distance (time) related phase issues and can sound pretty neat. I sometimes do this with the close drum overheads as it seems to make cymbal decay sweeter, i.e. I move the overhead tracks back in time to line up with the impulse from the snare.

Don't worry about it and align the phase in your DAW like Dave said. You could also use a phase alignment tool like the one from Little Labs.

use your ears not your eyes.

Yup, use your ears.

It's pretty easy to hear with mono summed parts in headphones. If you play guitar, it sounds almost identical to (surprise) a phaser pedal. Audition one mic by itself, then add in the second one. If when you add in the second one, it gives that phaser pedal type sound (gets washy and loses the bottom end) you have a phase problem and need to move the mic.

Hope this helps!

Tom

the littlelabs ibp wwon't align mics 3 feet apart. 3 inches maybe, but not 3 feet. if one mic is in the speaker an dthe other mic is 3 feet away ou probably won't havea phase prolblem