Studies have concluded that people progress through maslow's needs hierarchy as predicted. a. true b. false

That statement is False.
MAslow hierarchy of needs depict a clear path which indicates that people wouldn't be able to fulfill the needs on higher hierarchy if we haven't fulfill the needs on lower hierarchy.
Here's his hierarchy's arrangement from top to bottom:
- self actualization
- Self-esteem
- Love/belonging
- safety
- Physiological

But often times, we do not follow this hierarchy from bottom to top. (for example, some obsessed individual might want to sacrifice need for love/belonging as long as she could realized her life-long dream i.e: self-actualization)

Complementary goods. they go together, thats why one price increase and the others demand increases