Fill in the Blank with One of the Words or Phrases

Multiple Choice

Fill in the blank with one of the words or phrases listed below. Some words or phrases may be used more than once. $$\begin{array} { l l l l } \text { inverse } & \text { common } & \text { composition symmetric } & \text { exponential } \\\text { vertical } & \text { logarithmic } & \text { natural } \quad \text { half-life } & \text { horizontal }\end{array}$$
------------is the amount of time it takes for half of the amount of a substance to decay.

A) Exponential
B) Half-life
C) Composition
D) Logarithmic