The correct option is 2: full or new moon in association with the equinox.
Spring tides occur when the gravitational forces of the Moon and the Sun align, causing higher than average tides. These tides happen twice a month during the full and new moon phases. However, the intensity of spring tides can vary depending on other factors.
Option 1 suggests that the highest spring tides occur in association with the winter solstice. The winter solstice, which happens around December 21st, is the shortest day of the year and does not directly affect tidal activity. So, this option is incorrect.
Option 3 suggests that the highest spring tides occur in association with the summer solstice. The summer solstice, which happens around June 21st, also does not directly impact tidal activity. Therefore, this option is incorrect.
Option 4 states that high spring tides occur during both winter and summer solstices. However, as previously mentioned, solstices do not directly influence tidal activity. Therefore, this option is also incorrect.
Therefore, the correct answer is option 2, full or new moon in association with the equinox, as this is when the alignment of the Moon and the Sun`s gravitational forces can cause the highest spring