**Core Concept**
The question is testing the student's knowledge of the management of vocal cord paralysis, specifically in the context of diphtheria. Diphtheria can cause hoarseness of voice and vocal cord paralysis due to the toxin produced by the bacteria, which can affect the nerve supply to the vocal cord.

**Why the Correct Answer is Right**
The treatment of choice for paralyzed vocal cord is voice therapy, which involves exercises to improve vocal cord mobility and strength. This is the preferred option as it is non-invasive and has minimal side effects. In some cases, a speech therapist may recommend the use of a voice prosthesis to help improve vocal cord function.

**Why Each Wrong Option is Incorrect**
* **Option A:** Steroids are not the primary treatment for vocal cord paralysis, although they may be used in some cases to reduce swelling.
* **Option B:** Surgery is not typically the first line of treatment for vocal cord paralysis, especially in a child, unless there is a significant obstruction or other complications.
* **Option C:** Antibiotics may be used to treat the underlying infection, but they do not directly address the paralyzed vocal cord.

**Clinical Pearl / High-Yield Fact**
It's worth noting that diphtheria toxin can cause paralysis of the cranial nerves, including the vagus nerve, which supplies the vocal cord. This is why patients with diphtheria may experience hoarseness or vocal cord paralysis.

**Correct Answer:** C.