**Core Concept**
A submandibular mass with a mixed bacterial smear, including branched, gram-positive rods, suggests a diagnosis of actinomycosis, a rare chronic bacterial infection caused by Actinomyces species. These bacteria are part of the normal oral flora but can cause disease when they invade tissues.

**Why the Correct Answer is Right**
The correct answer is based on the pathophysiology of actinomycosis, which is characterized by the formation of granules (sulfur granules) and abscesses. Actinomyces species are known to invade tissues, leading to a chronic, destructive process. The presence of branched, gram-positive rods in the drainage supports this diagnosis. The most appropriate action is to initiate antibiotic therapy with penicillin, which is the treatment of choice for actinomycosis due to its bacteriostatic effects against Actinomyces species.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not address the specific diagnosis of actinomycosis. A simple incision and drainage may not be sufficient to treat the underlying infection.

**Option B:** This option is incorrect because it does not mention the use of antibiotics, which is essential for the treatment of actinomycosis.

**Option C:** This option is incorrect because it suggests a more aggressive surgical approach without addressing the underlying infection.

**Option D:** This option is incorrect because it does not provide a specific treatment plan for the patient.

**Clinical Pearl / High-Yield Fact**
Actinomyces species are part of the normal oral flora, but they can cause disease when they invade tissues. The presence of sulfur granules in the drainage is a classic diagnostic feature of actinomycosis.

**Correct Answer:** C. Surgical incision and drainage may be necessary, but it should be combined with antibiotic therapy to treat the underlying infection.