Step 1: Understanding myocardium.
The myocardium is the thick, muscular layer of the heart responsible for pumping blood. It is a specialized muscle tissue found only in the heart, making it different from other types of muscle tissues such as skeletal or smooth muscle.
Step 2: Analyzing the options.
(A) Brain: This is incorrect as the myocardium is not found in the brain.
(B) Heart: Correct — The myocardium is found only in the heart and plays a vital role in heart contractions.
(C) Stomach: This is incorrect, as the stomach contains smooth muscle, not myocardium.
(D) Lungs: The lungs do not contain myocardium; they contain smooth muscle tissue.
Step 3: Conclusion.
The correct answer is (B) Heart as myocardium is a special muscle tissue found only in the heart.