Answer: The correct answer is Option 3.
Step-by-step explanation:
Electrolyte is defined as a substance which dissociates into its ions in a solution and has a capacity to conduct electricity.
From the given options:
Option 1:

This compound belongs to ether group and it does not form ions when present in a solution. Thus, it is not considered as an electrolyte.
Option 2:

This compound is an alcohol and it dissociates into its ion but the ions formed are not stable. Hence, it is not considered as an electrolyte.
Option 3:

This compound is a carboxylic acid and it dissociates into its ion. The ions formed or the conjugate base formed are stable. Hence, it is considered as an electrolyte.

Option 4:

This compound is an aldehyde and it does not form ions when present in a solution. Thus, it is not considered as an electrolyte.
From the above information, the correct answer is Option 3.