Which of the following is called milk of magnesia?

 

Magnesium is effectively suspended in water, and because of the milk-like consistency of the suspension, it is known as milk of magnesia. 

Particles larger than 1000 nm in size that are visible to the naked eye are said to be in suspension. 
A milky-white liquid known as "milk of magnesia" is essentially magnesium hydroxide floating in water, along with sodium hypochlorite. Both a laxative and an antacid are common uses for it. Due to its basic composition, it neutralises the stomach's acid, demonstrating its usefulness as an antacid.
Milk of magnesia is the suspension of magnesium hydroxide, which occurs in the form of mineral brucite.