The most conspicuous salient feature of people with Progeria is a faster rate of aging, as stated in option 3. Progeria is a rare genetic disorder that causes rapid aging in children. These children appear to age at a much faster rate than normal. They usually start showing symptoms within the first year of life. Some common signs of Progeria include wrinkled skin, joint stiffness, hair loss, and a smaller stature.

Option 1, stating that people with Progeria have more hair on their body, is incorrect. In fact, individuals with Progeria often experience hair loss rather than an increase in hair growth.

Option 2, suggesting that people with Progeria have less immunity to opportunistic infections, is not the most prominent characteristic of this condition. While individuals with Progeria may indeed have weakened immune systems, the rapid aging is the most distinguishing feature.

Option 4, stating that people with Progeria suffer from infertility, is not a typical symptom of this condition. While individuals with Progeria may have developmental challenges and medical complications, infertility is not a consistently observed feature.

In summary, the correct answer is option 3, as the accelerated aging process is the most conspicuous feature of people with Progeria