Answer:
Subordinating conjunction.
Step-by-step explanation:
A subordinating conjunction is a conjunction that not only joins two sentences together but also acts as the link for the two clauses in such a way that the informative value of the whole sentence is made whole. This type of conjunction links a dependent clause with an independent clause.
In the sentence "I hopped on one foot while I pulled off the wet sock", the word "WHILE" acts as the subordinating conjunction. It helps join the two clauses together and also adds informational value to the first clause.
Thus, the correct answer is a subordinating conjunction.