Sounds like ADD (<span>Attention-Deficit Disorder).</span>
I think the answer is {b.false}
Infectious diseases are diseases that spread from one person to other either directly or indirectly. I think this is the answer.
An area with unifying characteristic is called as a region. The region is a broad geographic area, which is differentiated from other because of the similar features. In a region one or more than one types vegetational climax might be present. It is the continuous and extensive part of the surface. The area in a region is indefinite.
Hence, the given blank can be filled with region.