Answer:
The first step is - option A) an acid base reaction.
Step-by-step explanation:
The direct reaction of a carboxylic acid with an amine to form an amide is expected to be difficult as it would deprotonate the carboxylic acid and make a nonreactive carboxylate.
The first step in this reaction would be an acid - base reaction as protonation of the carbonyl carbon, that involves the interchange of proton in between electric charge or neutral compound, it is also known as protonation or deprotonation. The acid base reaction is followed by the nucleophilic attack on the carbonyl carbon.
Thus, The first step is - option A) an acid base reaction.