If C is graphed against F, the slope of the graph is equal to
degrees Celsius/degrees Fahrenheit, which means that for an increase of 1 degree Fahrenheit, the increase is
of 1 degree Celsius.
Thus, statement I is true.
This is the equivalent to saying that an increase of 1 degree Celsius is equal to an increase of
degrees Fahrenheit.
Since
=1.8, statement II is true.
On the other hand, statement III is not true, since a temperature increase of
degrees Fahrenheit, not
degree Fahrenheit, is equal to a temperature increase of 1 degree Celsius.
Choices A, B, and C are incorrect because each of these choices omits a true statement or includes a false statement.