To solve this problem, we need to determine why a frog's heart continues to beat after being removed from the body. Let's analyze each statement:$\newline \bullet$(a) Frog is a poikilotherm:$\newline$ - Poikilotherms are organisms whose internal temperature varies considerably.$\newline$ - This characteristic does not directly explain why the heart continues to beat outside the body.$\newline \bullet$(b) Frog does not have any coronary circulation:$\newline$ - Coronary circulation refers to the blood supply to the heart muscle itself.$\newline$ - The absence of coronary circulation is not related to the heart's ability to beat outside the body.$\newline \bullet$(c) Heart is myogenic in nature:$\newline$ - A myogenic heart can initiate its own contractions without external stimuli.$\newline$ - This property allows the heart to continue beating even when removed from the body.$\newline \bullet$(d) Heart is auto-excitable:$\newline$ - An auto-excitable heart can generate its own electrical impulses, leading to continuous beating.$\newline$ - This is another reason why the heart can beat outside the body.$\newline$Based on the analysis, the correct explanation involves both the myogenic and auto-excitable nature of the heart.$\newline$Therefore, the correct option is Option 3: (c) and (d).