**Core Concept**
RPD (Removable Partial Denture) is a dental prosthesis designed to replace missing teeth in a patient's mouth, while still allowing the remaining teeth to function naturally. The design and fabrication of RPDs depend on several factors, including the location and extent of tooth loss, the remaining alveolar bone, and the patient's occlusal scheme.

**Why the Correct Answer is Right**
RPDs are generally indicated in patients with single or multiple edentulous spaces, where the remaining teeth are still present and can provide sufficient support for the prosthesis. However, in cases of multiple edentulous spaces, it may be challenging to achieve adequate support and stability for the RPD, making it a less ideal option. This is because multiple edentulous spaces often result in a more extensive loss of alveolar bone, which can compromise the support and retention of the RPD.

**Why Each Wrong Option is Incorrect**
**Option A:** Long edentulous span is actually an indication for RPD, as it allows for better distribution of forces and more even support for the prosthesis.
**Option C:** Excessive loss of alveolar bone is a common indication for RPD, as it can provide a more stable and long-lasting solution for patients with significant tooth loss.
**Option D:** Distal abutment loss can also be an indication for RPD, as it can provide additional support and stability for the prosthesis.

**Clinical Pearl / High-Yield Fact**
When considering RPDs, it's essential to assess the patient's overall oral health, including the remaining alveolar bone, the occlusal scheme, and the distribution of forces. A thorough examination and diagnosis can help determine the most suitable treatment option for the patient.

✓ Correct Answer: B. Multiple edentulous spaces