Answer:
Ethanol
Step-by-step explanation:
Solvent extraction is the process in which a compound transfers from one solvent to another owing to the difference in solubility or distribution coefficient between these two solvents(Science Direct).
We have to remember that oxalic acid will be extracted better into a solvent in which it is more soluble. From the data given; oxalic acid is more soluble in ethanol than in ether.
This simply means that ethanol is a better solvent for extracting oxalic acid from water when compared to ether.