Step 1: Understanding the Concept
Functional isomers have the same molecular formula but different functional groups.
Step 2: Compare Formulas
Saturated ethers and saturated alcohols both have the formula \(\text{C}_{n}\text{H}_{2n+2}\text{O}\).
For example, \(\text{C}_{2}\text{H}_{6}\text{O}\) is ethanol or dimethyl ether.
Step 3: Check the Others
Aldehydes, ketones and acids have the formula \(\text{C}_{n}\text{H}_{2n}\text{O}\) or \(\text{C}_{n}\text{H}_{2n}\text{O}_{2}\), which differs from ethers.
Final Answer:
Alcohols are functional isomers of ethers, option (C).
\[ \boxed{\text{(C) }\text{Alcohols}} \]