Ricardian equivalence:
a. occurs when people see that lower taxes today means higher taxes in the future, so instead of spending their tax cut, they save it to pay future taxes.
b. is the decrease in private spending that occurs when government increases spending.
c. is federal government policy on taxes, spending, and borrowing that is designed to influence business fluctuations.
d. is central bank policy on the monetary base, interest rates, and bank reserves that is designed to influence business fluctuations.

Ricardian equivalence:

a. Occurs when people see that lower taxes today means higher taxes in the future, so instead of spending their tax cut, they save it to pay future taxes.

Explanation:

The Ricardian equivalence is a theory given by the English economist David Ricardo in the 19th century, where he suggests that the fiscal deficit (when the nation spends more than obtain) doesn't affect the aggregate demand (the possibility of the country to acquire products) by two reasons:

1. Finances the spend with more high taxes, it could occur in the present or in the future, but if the people see that the taxes are low and the country is spending, they save money for the future higher taxes.  

2. increasing external debt.    

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)