One of the statements below contains a word used incorrectly or inappropriately. Choose the option which has the incorrect or inappropriate usage of the word.

The word cord appears in all four sentences and has multiple meanings. Traditionally, it refers to a thin, flexible length of rope or string, often used for tying or fastening things. It can also have specific meanings depending on context—for example, an umbilical cord in biology, a cord of wood as a unit of measurement for firewood, or a neck cord used to hold objects like keys.

We look at each option one by one . 

Option A: Teenagers may feel a need to cut the umbilical cord tying them to their homes.

Here, cord is used correctly.  Umbilical cord is the correct term for the metaphor of emotional or dependent ties to home.

Option B: The musician would hear a cord in his head and play each note individually.

Here, the word cord is used incorrectly; the correct word should be chord. (A chord in music is a group of notes played together)

Option C: He purchased a cord of wood from the market.

Here, the use of cord is correct, as it is used as a unit of measurement for firewood.

Option D: To keep the key safe, she wore it on a cord around her neck.

Here, the use of cord is correct as well, as cord here means a thin rope or string — appropriate in this context.

Hence, option B is the correct answer.