Answer
The answer is attached below.
Work Step by Step
Fructose ( $C_{6}$ $H_{12}$ $O_{6}$ ) , is a simple sugar. Due to the presence of C=O, it is a ketose sugar.
The OH group on carbon number 5 reacts with C=O of carbon number 2. C=O is converted to C-OH group and an ether group ( R-O-R' ) is formed between carbon number 2 and carbon number 5. In this way, the ring structure of fructose is formed.
