The most susceptible compound to nucleophilic attack at the carbonyl carbon among the given bellow group is

Step-by-step solution

Amongst aldehyde & the acid derivatives, acid chloride are the most susceptible to nucleophilic attack due to strong - I effect & weak + R effect of the C l - atom as a result of which carbonyl carbon has the highest electron deficiency. The actual order is M e C O C l > M e C O O C O M e > M e C O O M e > M e C H O .