**Core Concept**
MRI (Magnetic Resonance Imaging) uses a strong magnetic field and radio waves to produce detailed images of the body's internal structures. However, the presence of certain materials can interfere with the magnetic field, causing artifacts or even posing a risk to the patient.

**Why the Correct Answer is Right**
MRI is unsuitable for individuals with **cardiac pacemakers** (Option A), as the strong magnetic field can interfere with the pacemaker's functioning, potentially leading to life-threatening arrhythmias. Similarly, **metallic clips** (Option B) can cause artifacts or distortions in the MRI images, compromising diagnostic accuracy. Additionally, **woody items** (Option C) are not typically a concern in MRI, but it's worth noting that ferromagnetic objects, including metal fragments, can be hazardous in an MRI environment. However, "woody items" is an uncommon distractor in this context, and the primary concern is with ferromagnetic materials like pacemakers and metallic clips.

**Why Each Wrong Option is Incorrect**
**Option C:** While "woody items" might seem like a plausible distractor, it's not a typical concern in MRI. The primary issue is with ferromagnetic materials that can interact with the strong magnetic field.

**Clinical Pearl / High-Yield Fact**
When preparing patients for MRI, it's essential to screen for the presence of any ferromagnetic materials, including cardiac pacemakers, metallic clips, and other metal fragments. A thorough medical history and physical examination can help identify potential risks and ensure safe imaging.

**✓ Correct Answer: D. All of the above**