Professor Sanford explains that the need for physical safety must be met before city dwellers will be motivated to form close friendships with fellow citizens. Professor Sanford is providing an example of

a hierarchy of needs

Explanation:

The Professor Sanford has provided an example of a hierarchy of needs which is a psychological theory given by Maslow. According to this law, when a deficit need is fulfilled or satisfied one goes towards another step of fulfilling or satisfying another set of needs.

Maslow initially stated the fact that individuals must satisfy the lower level of deficit needs before succeeding to meet the high levels of growth requirements.

Professor Sanford is explaining that physical safety is the basic need which must be met before the city dwellers develop a close friendship with the fellow citizens.

they all focused on themes about the inevitability of death.

the earth’s crust is broken into separate pieces called tectonic plates (fig. 7.14). recall that the crust is the solid, rocky, outer shell of the planet. it is composed of two distinctly different types of material: the less-dense continental crust and the more-dense oceanic crust. both types of crust rest atop solid, upper mantle material. the upper mantle, in turn, floats on a denser layer of lower mantle that is much like thick molten tar.

each tectonic plate is free-floating and can move independently. earthquakes and volcanoes are the direct result of the movement of tectonic plates at fault lines. the term fault is used to describe the boundary between tectonic plates. most of the earthquakes and volcanoes around the pacific ocean basin—a pattern known as the “ring of fire”—are due to the movement of tectonic plates in this region. other observable results of short-term plate movement include the gradual widening of the great rift lakes in eastern africa and the rising of the himalayan mountain range. the motion of plates can be described in four general patterns:

collision: when two continental plates are shoved together

subduction: when one plate plunges beneath another (fig. 7.15)

spreading: when two plates are pushed apart (fig. 7.15)

transform faulting: when two plates slide past each other (fig. 7.15)