Final answer:
Hypocalcemia, characterized by low levels of calcium in the blood, is the condition that leads to symptoms such as hyperirritability, tetany, and electrocardiogram changes, affecting neuromuscular function. Option B is correct.
Step-by-step explanation:
The best-defined manifestation of electrolyte deficiency involving hyperirritability, tetany, and electrocardiogram changes is hypocalcemia. This condition is characterized by abnormally low levels of calcium in the blood and can significantly affect neuromuscular function.
Essential for various bodily functions, calcium aids in blood coagulation, muscle contractions, nerve signaling, and bone strength. In cases of hypocalcemia, patients can experience muscle spasms, cardiac rhythm disturbances, and even seizures due to increased neuromuscular excitability.
Although similar symptoms may be seen with other electrolyte imbalances, the specific combination of symptoms described fits best with hypocalcemia. Therefore, the correct answer to this question is b) Hypocalcemia.