Explanation:

An osazone derivative is a compound formed by the reaction of a reducing sugar with phenylhydrazine. It is commonly used to identify and characterize sugars. The reaction between a reducing sugar and phenylhydrazine results in the formation of a yellow-orange crystalline compound called an osazone.

To determine which compound will form an osazone derivative, we need to identify the compound that is a reducing sugar. A reducing sugar is a sugar that is capable of reducing other substances, such as metal ions or phenylhydrazine. This ability to reduce other substances is due to the presence of a reactive carbonyl group (aldehyde or ketone) in the sugar molecule.

Identifying the reducing sugar:

Let's analyze each compound to identify the presence of a carbonyl group:

a) CH3CH2CHOHCH2OH: This compound does not contain a carbonyl group. It is a sugar alcohol and does not have the ability to reduce other substances.

b) CH3COCH2CH2OH: This compound contains a carbonyl group in the form of a ketone. Ketones are not typically considered reducing sugars unless they can tautomerize into an aldehyde form. However, this compound does not have any tautomeric aldehyde form. Therefore, it is not a reducing sugar.

c) CH3CH2COCH2OH: This compound contains a carbonyl group in the form of an aldehyde. Aldehydes are known to be reducing sugars as they can undergo oxidation-reduction reactions. Therefore, this compound is a reducing sugar and will form an osazone derivative.

d) CH3CH2COCH2OCH3: This compound contains a carbonyl group in the form of a ketone. As mentioned earlier, ketones are not typically considered reducing sugars unless they can tautomerize into an aldehyde form. However, this compound does not have any tautomeric aldehyde form. Therefore, it is not a reducing sugar.

Conclusion:

Based on the presence of a carbonyl group, the compound that will form an osazone derivative is option 'c' CH3CH2COCH2OH.