The release of energy stored in ATP molecules take place when it-
(a)Passes electrons to NADH
(b)Splits into a phosphate ion and ADP
(c)Loses electron and becomes ADP
(d)Breaks its bond and loses all its phosphate ion
(e)Breaks the bond within one of its phosphate group

Hint: One adenosine and three (tri) phosphate groups are composed of an ATP molecule. Adenosine diphosphate (ADP), which is the remaining adenosine and two (di) phosphate groups, and one single 'alone' phosphate (Pi) are the by-products of ATP breakdown.

Complete answer:
The energy currency of life is adenosine triphosphate (ATP). The energy produced in mitochondria is stored in the form of ATP during cellular respiration. Via its separation into ADP and Pi, it provides energy for all life activities. ATP comprises three classes of phosphates that have a high energy bond. Energy is released from ATP hydrolysis and ADP is formed. This reaction is generally referred to as the hydrolysis of ATP because the basic reaction requires a water molecule,
ATP+Water\longrightarrow ADP+Pi

Additional Information: ADP stands for adenosine diphosphate, and not only is it one of the body's most important molecules, but it is also one of the most numerous. ADP is an ingredient for DNA, it is important for muscle contraction, and when a blood vessel is broken, it also helps initiate healing.
A cofactor essential to metabolism is the nicotinamide adenine dinucleotide. NAD is considered a dinucleotide present in all living cells because it consists of two nucleotides connected by their phosphate groups. The adenine nucleobase and the other nicotinamide contain one nucleotide.
So, the correct answer is ‘Splits into a phosphate ion and ADP’.

Note: The nucleotide known in biochemistry as the "molecular currency" of intracellular energy transfer is the adenosine triphosphate (ATP) molecule; that is to say, ATP can store and transport chemical energy within cells. In the synthesis of nucleic acids, ATP also has a significant role.