C & B are switched so I'm not sure if that was a typo or not, but the answer is concentration!
Answer: b. The waste generated is hazardous and must be disposed of.
c. Nuclear material can be spilled into the ocean if reactors are near the coast.
d. A large amount of cold water is generated, which must be stored somewhere.
Explanation:
The main environmental costs for produced during the nuclear power plant consists of procurement of fuel and the thermal load is also produced with cold water discharge in the sea. This can contaminate the sea, hence, must be stored somewhere. The nuclear waste consists of radioactive substances which are hazardous for the environment. The nuclear based electricity does not produce carbon dioxide.
It is know as the normal force.
When a solid is placed on a support, the latter exerts forces on the solid at each point of contact. These are forces that oppose the weight and prevent an object from falling.
This force is usually vertical and upward and often offsets the weight. If the solid is in equilibrium on the support the forces compensate the weight of the solid.