**Core Concept**
Elastic cartilage is a type of connective tissue found in the body, characterized by the presence of elastic fibers. This type of cartilage provides flexibility and support to the structures it is found in.

**Why the Correct Answer is Right**
Elastic cartilage is primarily found in the external ear, epiglottis, and auditory tube. The elastic fibers in this cartilage allow for significant flexibility and movement in these structures. The unique composition of elastic cartilage enables it to resist deformation and return to its original shape after being stretched. This property is essential for the proper functioning of the external ear, which requires precise movement to detect sounds.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because elastic cartilage is not typically found in the nasal septum, which is usually composed of hyaline cartilage.
**Option B:** This option is incorrect because elastic cartilage is not found in the menisci of the knee joint, which are composed of hyaline cartilage.
**Option C:** This option is incorrect because elastic cartilage is not found in the costal cartilages, which are composed of hyaline cartilage.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the type of cartilage found in a particular structure is often related to its functional requirements. For example, the external ear requires elastic cartilage to facilitate movement, while the nasal septum requires hyaline cartilage to provide support.

**Correct Answer:** C.