Hey there!
So, from reviewing this question listed above, the key point that we would want to consider is what would he a (example) of applied chemistry.
So, in your options listed, let's find one what would have a (method of producing) some element or chemical that would be a great example of (applied chemistry)
Your correct answer: A perfecting a method for producing nylon fibers.
Reason/Justification:
So,when we are trying to find a applied example of a applied chemical or even a applied substance or even a element,we would want to find something that would PRODUCE and make things from one element (FROM) another.
So,in this case from your options, we have (nylon) being produced through perfecting a certain method which thus from this,would be another substance, or element to help make this.
Your correct answer would he option (A).
I hope this helps you!