Which of the following describes an exothermic reaction?

a + b imported asset ab + heat

a + bδ imported asset ab

heat + bc imported asset b + c

b + heat + cd imported asset bd + c

The answer to your question is:  letter A

Explanation:

a) A + B ⇒ AB + heat     It is an exothermic reaction because heat is released.

b) A + BΔ ⇒ AB  It heat added to the reactants , then it is an endothermic reaction.

c) heat + BC ⇒ B + C  It's an endothermic reaction because heat is added to the reactants.

d) B + heat + CD ⇒ BD + C  It's and endothermic reaction because heat is added to the reactants.