Flowers & fruit is the answerrrr
The correct choice is that it extends until depths of around 60 m where sediments cannot move anymore. The important thing is that it certainly is not just the contact point of water and land; it goes into the sea until this point, where also enough light reaches the bottom for plants to do photosynthesis. D is wrong because breakers do not play a role in this definition, although it can vary from context to context (sea, lakes etc.).
I know that some plant cells are made from cellulose, and one of the main goals of the cell wall is to strengthen and support the cell. So, I think, the answer(s) are: cellulose and increased strength to the cell