When does a perigean spring tide typically occur?

A perigean spring tide occurs when there is a new or full moon that coincides closely in time with lunar perigee, which is the point in the moon's orbit where it is closest to Earth. This close proximity increases the gravitational pull of the moon on the Earth’s waters, leading to exceptionally high and low tides, known as spring tides.

The alignment of the moon's phases—either new or full—elaborates on the tidal range, while the timing of the moon being at perigee enhances this phenomenon. This is why option C is the correct answer, as it captures the essential conditions necessary for a perigean spring tide to occur.

In contrast, a perigean spring tide does not strictly occur only during a full moon, as suggested by the first option, because it can also happen during a new moon. The second option, involving a new moon at apogee, is contradictory to the phenomenon itself; apogee is when the moon is farthest from the Earth, which would not enhance tidal effects. The fourth option relates to the solstices, which is not relevant since spring tides can happen multiple times throughout the year and are not limited to the solstices.