**Core Concept**
The VDRL test is a non-treponemal test used for screening syphilis, which detects the presence of antibodies against the lipoidal material released from damaged host cells and treponemes. A reactive test result indicates exposure to syphilis, but it cannot differentiate between active and latent infection.

**Why the Correct Answer is Right**
A reactive VDRL test in a patient with a painless penile ulcer is suggestive of primary syphilis. However, the patient's recent diagnosis of hepatitis A may affect the test result due to the presence of heterophile antibodies, which can cause false-positive reactions. The correct approach is to perform a confirmatory test, such as the Treponema pallidum particle agglutination assay (TP-PA), to confirm the diagnosis of syphilis.

**Why Each Wrong Option is Incorrect**
**Option A:** Performing a complete blood count (CBC) and liver function tests (LFTs) is not directly relevant to the diagnosis of syphilis. While it may provide information on the patient's overall health, it does not address the need for a confirmatory test.
**Option B:** Administering penicillin is premature without confirming the diagnosis of syphilis. If the patient has syphilis, treatment is necessary, but the correct diagnosis must be established first.
**Option C:** Collecting a cerebrospinal fluid (CSF) sample is not necessary at this stage. While a CSF-VDRL test is used to diagnose neurosyphilis, this patient's presentation does not warrant such an investigation.

**Clinical Pearl / High-Yield Fact**
When interpreting non-treponemal tests like the VDRL, keep in mind that false-positive results can occur due to various conditions, including infections, autoimmune disorders, and even pregnancy. Always confirm the diagnosis with a treponemal test, such as the TP-PA, to avoid misdiagnosis.

**Correct Answer:** B.