**Core Concept**
Rheumatoid arthritis (RA) is a chronic autoimmune disorder characterized by inflammation of the synovial joints, leading to pain, stiffness, and eventual destruction of the joint. The 1987 modified American Rheumatism Association (ARA) criteria for diagnosing RA emphasize the presence of certain clinical and laboratory features, including joint involvement.

**Why the Correct Answer is Right**
According to the 1987 modified ARA criteria, the joints that are typically involved in RA are the proximal interphalangeal (PIP) joints, metacarpophalangeal (MCP) joints, wrists, knees, elbows, ankles, and shoulders. The criteria specifically exclude the involvement of the sternoclavicular joints, which are not typically affected in RA. This is because the sternoclavicular joints are not a common site of synovitis in RA, and their involvement may suggest other conditions such as psoriatic arthritis or osteoarthritis.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the PIP joints are a common site of involvement in RA.
**Option B:** This option is incorrect because the MCP joints are also commonly involved in RA.
**Option C:** This option is incorrect because the wrists are a typical site of involvement in RA.
**Option D:** This option is incorrect because the shoulders are also commonly affected in RA.

**Clinical Pearl / High-Yield Fact**
When considering the diagnosis of RA, it's essential to remember that the 1987 modified ARA criteria emphasize the presence of morning stiffness lasting at least 1 hour, arthritis of at least three joints, and the presence of rheumatoid nodules or a positive rheumatoid factor.

**Correct Answer:** D. Sternoclavicular joint.