What type of seashore has the most diversity

The correct answer is: rocky seashore.

A rocky seashore is an area (an exposed or sheltered area) of the seacoasts where solid rock predominates, (it also have boulders and pebbles). Rocky seashores are rich environments, meaning that many plants and animals are adapted to live in such habitat. It is challenging place to live, because of the continual cycle of changing tides.