The correct answer is C) he gave Arthur a round table given to him by Arthur's father, King Uther.
Instead of land, the gift that King Leodegrance decided to give King Arthur for Gwenevere's dowry was a round table given to him by Arthur's father, King Uther.
There are many stories about the origins of King Arthur's round table. But many consider that King Leodegrance, King of Cameliard, was very happy for the marriage of his daughter Gwenevere and King Arthur. So knowing that Arthur already had money, possessions, and land, he thought of a creative and important wedding gift. That is when he thought on give his the round table once given to him by Arthur's father, King Uther.
The other options of the question were a) his remaining 100 knights build Arthur a round table, b) he allowed Gwenevere to take all of her belongings so she would feel at home, and d) he decided to build a home for them to live in and raise their family.