During summer, the northern hemisphere of earth is
cooler than the southern hemisphere
tilted toward the sun
tilted away from the sun
furthest from the sun

The correct answer is - tilted toward the Sun.

During summer, the Northern Hemisphere is tilted towards the Sun. That is actually the reason why it is a summer in that period of the year, because with it being tilted towards the Sun, it receives more sunlight, thus being warmer.

The Southern Hemisphere, when it is summer on the Northern Hemisphere, experiences winter, and that is because it is tilted away from the Sun, thus receiving less sunlight. When it is summer in the Southern Hemisphere though, than it is winter in the Northern Hemisphere, and the reason for that is that the Southern Hemisphere is the one tilted towards the Sun, while the Northern Hemisphere is tilted away from it.

a. i. only is correct.