**Core Concept**
The question is about the consequences of an infection in the ulnar bursa, which is a synovial sheath surrounding the tendons in the hand. The underlying principle being tested is the anatomy and function of the tendons in the hand and the potential complications of bursitis.

**Why the Correct Answer is Right**
The ulnar bursa is a synovial sheath that surrounds the ulnar collateral ligament and the ulnar bursa tendon, which is a part of the flexor digitorum profundus (FDP) tendon. The infection in the ulnar bursa can lead to necrosis of the FDP tendon due to the impaired blood supply. The FDP tendon is responsible for flexion of the distal interphalangeal joints of the fingers.

**Why Each Wrong Option is Incorrect**
* **Option A:** The radial bursa surrounds the extensor tendons, which are not directly affected by an infection in the ulnar bursa.
* **Option B:** The palmar bursa surrounds the flexor tendons, but the specific tendon affected by an infection in the ulnar bursa is the FDP tendon, not the flexor digitorum superficialis (FDS) tendon.
* **Option C:** The pisiform bursa surrounds the flexor carpi ulnaris tendon, which is not directly affected by an infection in the ulnar bursa.

**Clinical Pearl / High-Yield Fact**
Infections in the hand can lead to necrosis of the tendons due to impaired blood supply, leading to permanent damage and loss of function. Prompt treatment of infections in the hand is essential to prevent long-term complications.

**Correct Answer:** B.