**Core Concept**
Isoniazid (INH) is a first-line antitubercular medication used in the treatment of tuberculosis (TB). The daily dose of INH is critical in managing TB effectively while minimizing side effects.

**Why the Correct Answer is Right**
The recommended daily dose of INH for TB is 5 mg/kg, not to exceed 300 mg. This dose is sufficient to inhibit the growth of Mycobacterium tuberculosis while minimizing the risk of hepatotoxicity. INH works by inhibiting the synthesis of mycolic acid, a critical component of the TB bacterium's cell wall.

**Why Each Wrong Option is Incorrect**
* **Option B:** This option may be a higher dose, but it increases the risk of hepatotoxicity and is not necessary for most patients.
* **Option C:** This option is lower than the recommended dose and may lead to inadequate treatment of TB.
* **Option D:** This option is not relevant to the treatment of TB and is therefore incorrect.

**Clinical Pearl / High-Yield Fact**
Remember, the daily dose of INH should not exceed 300 mg, and the dose should be adjusted based on the patient's weight to minimize the risk of hepatotoxicity.

**Correct Answer: A. 5 mg/kg, not to exceed 300 mg.**