Baseball Dirt Dirt Is Not Dirt When It Comes to Baseball Fields

Baseball Dirt
Dirt is not dirt when it comes to baseball fields. About two-thirds of the pro baseball fields get their dirt from a dirt farm in New Jersey called Partac Peat. The company markets a secret mix for the infield (resilient) , the warning track (extra crunchy) , and the pitcher's mounds (firm) . Mounds come in red, brown, orange, and gray colors. Roger Bossard, the White Sox head groundskeeper, scouted nationwide for dirt before settling on the mix provided by Partac Peat. (He uses sand under the grassy areas of the playing field.)
-Refer to Baseball Dirt.Some of the dirt sold by Partac Peat is used to make clay tennis court surfaces.As the number of people playing tennis increases,so does the demand for new clay courts and,therefore,the demand for Partac Peat's dirt.This occurs because the demand for the dirt is:

A) inelastic.
B) intangible.
C) heterogeneous.
D) derived.
E) elastic.