Which of these statements about the human ear is true ?

Options

A. Th Crista and macula are the specific receptors of the vestibular apparatus responsible for maintenance of balance of the body and posture .
B. The fluid between bony labyrinth and membranous labyrinth is endolymph
C. The lateral most ear ossicle is stepes while the medial most ear ossicles is malleus
D. A large number of processes called stereo cilia are projected from the basal part of each hair cell of organ of corti

Answer

To determine which statement about the human ear is true, we will analyze each statement one by one.

### Step 1: Analyze the First Statement
**Statement:** The crista and macula are the specific receptors of the vestibular apparatus responsible for the maintenance of balance of the body and posture.

- **Explanation:** The vestibular apparatus, located in the inner ear, contains structures called the crista and macula. These structures are indeed responsible for detecting changes in head position and motion, thus helping maintain balance and posture. Therefore, this statement is **true**.

### Step 2: Analyze the Second Statement
**Statement:** The fluid filled bony labyrinth and membranous labyrinth is called endolymph.

- **Explanation:** The inner ear consists of two labyrinths: the bony labyrinth and the membranous labyrinth. The fluid inside the membranous labyrinth is called **endolymph**, while the fluid in the space between the bony and membranous labyrinth is called **perilymph**. Therefore, this statement is **false**.

### Step 3: Analyze the Third Statement
**Statement:** The most lateral ear ossicle is Taps while the middle most ear ossicle is Malus.

- **Explanation:** The three ear ossicles are the malleus, incus, and stapes. The malleus is the most lateral (outermost), followed by the incus, and the stapes is the innermost (medial). The statement incorrectly names "Taps" instead of "malleus" and misidentifies the positions. Therefore, this statement is **false**.

### Step 4: Analyze the Fourth Statement
**Statement:** A large number of processes called stereocilia are projected from the basal part of each hair cell of the organ of Corti.

- **Explanation:** In the organ of Corti, which is located on the basilar membrane of the cochlea, the stereocilia (hair-like projections) actually project from the **apical** part of the hair cells, not the basal part. Therefore, this statement is **false**.

### Conclusion
After analyzing all the statements, the only true statement is the first one: **The crista and macula are the specific receptors of the vestibular apparatus responsible for the maintenance of balance of the body and posture.**