According to a set of standards, a certain type of substance can contain a maximum of

The correct answer is $.0014$. It's given that a certain type of substance can contain a maximum of $0.001\%$ phosphorus by mass to meet a set of standards. If a sample of the substance has a mass of $140$ grams, it follows that the maximum mass, in grams, of phosphorus the sample can contain to meet the standards is $0.001\%$ of $140$, or $\frac{0.001}{100}\left(140\right)$, which is equivalent to $\left(0.00001\right)\left(140\right)$, or $0.0014$. Note that .0014 and 0.001 are examples of ways to enter a correct answer.