Which of the following reagents are used to distinguish aldehydes from Ketones? 

I) Fehling’s reagent 

II) Lucas reagent 

III) Heinsberg’s reagent 

IV) Tollen’s reagent 

Fehling’s solution is complex of $aq.CuS{O}_4$ which gives red precipitate when reacted with aldehyde and Cu(II) ions are reduced to metal but ketone does not show any reactivity. 

Tollen’s reagent is silver ammonia complex which oxidises aldehyde to carboxylic acid and silver ions are reduced to silver metal giving silver mirror on sides of test tube but this action is not shown by ketones as it is mild oxidising agent. 

Therefore, the correct answer is option (D) I, IV