When a block of wood with a weight of 30 \mathrm{~N} is completely submerged under water the buoyant force on the block of wood from the water is 50 \mathrm{~N}. When the block is released it floats at the surface. What fraction of the block will then be visible above the surface of the water when the block is floating?
Answer Choices
A. 1 / 15
B. 1 / 5
C. 1 / 3
D. 2 / 5
E. 3 / 5