A leader so your answer would be c
When using logic or common sense to solve problems that will be protected
The vES ending should be added to nouns that end in -f or -fe in their singular form. In that case, the -f or -fe is removed and -ves is added as a plural ending. Examples include: life - lives, wife - wives, knife - knives, wolf - wolves, leaf - leaves. But there are also exceptions, such as belief - beliefs, cliff - cliffs, roof - roofs.
Yes it is diffusion ..
explanation :
diffusion is the movement of particles from high concentration to low concentration ..
as the smoke rises at one corner of the room soon it spreads all over the room which is simply diffusion ..
I am going to go with C (simple sentence) on this one because after the and you do not have another complete sentence therefore it would not be considered a complex sentence. Hopefully this helps.