What are geographic concepts, and how are they used in answering geographic questions?

Geographic concepts are ideas which posit connections between humans in both natural and cultural settings, they are connected to space and proximity and offer geographers a lens in which to consider and present information that they conclude about the world. Based upon these conclusions that can be drawn from these concepts, geographic questions can be answered with evidence from how humans interact with the world. 

The sun's parallax would be 180 degrees, greater than which you can't get.  so a. would be your anwser 

Answerequatorial guinea,gabon, and western sahara;