All of the following are useful blending tools when creating pencil drawings, except which?
a. gum
c. shammy
b. eraser
d. tortillians

The correct answer is a. gum. Gum is actually a type of eraser, softer than a normal Pink Pearl eraser, that crumbles away upon use. So, instead of blending or shading a pencil drawing, gum would actually erase it. A shammy is a chamois cloth, which is a natural skin, and a tortillion is cylindrical tool made of rolled-up paper, both of which are used for blending charcoals. An eraser can be useful in blending to create a softer look, for example when drawing clouds in the sky.