Why does the winter and summer solstice occur at different times in the northern hemisphere rather than that of the southern hemisphere

Earth's tilted axis causes the seasons. Throughout the year, different parts of Earth receive the Sun's most direct rays. So, when the North Pole tilts toward the Sun, it's summer in the Northern Hemisphere. And when the South Pole tilts toward the Sun, it's winter in the Northern Hemisphere.

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

Answer steam fog;