Answer:
B. Calcium (Element Symbol: Ca)
Step-by-step explanation:
Analysis of each element/compound:
(Option A): Sodium is a soft, silver-white, metallic element that oxidizes rapidly in moist air, occurring in nature only in the combined state and used in the synthesis of sodium peroxide, sodium cyanide, and tetraethyllead: a necessary element in the body for the maintenance of normal fluid balance and other physiological functions. Symbol: Na; atomic weight. 22.9898; atomic number: 11; specific gravity: 0.97 at 20°C.
(Option B): Calcium is a silver-white divalent metal, occurring combined in limestone, chalk, gypsum, etc., occurring also in vertebrates and other animals, as a component of bone, skeletal mass, shell, etc., and as a necessary element in nerve conduction, heartbeat, muscle contraction, and many other physiological functions. Symbol: Ca; atomic weight: 40.08; atomic number: 20; specific gravity: 1.55 at 20°C.
(Option C): Potassium is a silvery-white metallic element that oxidizes rapidly in the air and whose compounds are used as fertilizer and in special hard glasses. Symbol: K; atomic weight: 39.102; atomic number: 19; specific gravity: 0.86 at 20°C.
(Option D): Chloride is a salt of hydrochloric acid consisting of two elements, one of which is chlorine, as sodium chloride, NaCl.
(Chlorine is a halogen element, a heavy, greenish-yellow, incombustible, water-soluble, poisonous gas that is highly irritating to the respiratory organs, obtained chiefly by electrolysis of sodium chloride brine: used for water purification, in the making of bleach powder, and in the manufacture of both chemical that do not contain chlorine, as ethylene glycol, and those that do. Symbol: Cl; atomic weight: 35.453; atomic number: 17). (Sodium chloride is a salt, a crystalline compound, sodium chloride, NaCl, occurring as a mineral, a constituent of seawater, etc., and used for seasoning food, as a preservative, etc. )
From closer analysis, it can be said that calcium triggers contraction in striated muscle.
Thank you,
Eddie