**Core Concept:** Respiratory distress syndrome (RDS) is a common condition in premature infants, caused by the insufficient production of surfactant - a substance that prevents lung alveoli from collapsing. RDS leads to alveolar flooding and hypoxia, resulting in abnormal breathing patterns and signs.

**Why the Correct Answer is Right:** The correct answer, **D:** "Increased work of breathing and grunting" is indicative of RDS in newborns. This is because RDS causes premature infants to use more energy to breathe due to the immature lungs and ineffective gas exchange. The increased effort results in a pattern of rapid, shallow breaths known as grunting.

**Why Each Wrong Option is Incorrect:**

A. **Increased respiratory rate:** While an increased respiratory rate is a common finding in RDS, the correct answer focuses on the increased work of breathing and grunting rather than just the increased respiratory rate.

B. **Less respiratory distress:** This option contradicts the essence of RDS, which is characterized by respiratory distress and increased work of breathing.

C. **Normal breathing pattern:** This option is incorrect as RDS causes abnormal breathing patterns, not normal ones.

**Clinical Pearl:** A high suspicion index for RDS is crucial, especially with premature infants, as early diagnosis and treatment can improve outcomes.

**Explanation:**

RDS is a common respiratory disorder in premature infants, caused by the immature lungs and insufficient surfactant production. The condition leads to alveolar flooding and hypoxia, resulting in increased work of breathing and grunting, which is why the correct answer focuses on these signs.

While an increased respiratory rate is a common finding in RDS, the correct answer, option D, emphasizes the increased work of breathing and grunting, signifying the abnormal breathing patterns associated with RDS.

RDS is typically diagnosed in premature infants, and early recognition and treatment can significantly improve the outcome.