Final answer:
The question is asking about the result of performing a series of substitutions on the expression nx.
Step-by-step explanation:
The question is asking about the result of performing a series of substitutions on the expression nx. Each option represents a different substitution. Let's go through each option one by one:
Replace x with 1. So, nx becomes n1.
Replace x with 2. So, nx becomes n2.
Replace x with 3. So, nx becomes n3.
Replace x with 4. So, nx becomes n4.