**Core Concept**
The cardinal movements of labor refer to the sequential changes in the fetal head's position and rotation that occur during the process of vaginal delivery. These movements are crucial for the safe passage of the fetus through the birth canal.

**Why the Correct Answer is Right**
The correct sequence of cardinal movements in labor is as follows: Engagement, Descent, Flexion, Internal Rotation, Extension, and External Rotation. Engagement occurs when the presenting part of the fetus (usually the head) reaches the pelvic inlet. Descent follows, where the head moves down into the pelvis, aligning with the pelvic axis. As the head descends, it undergoes flexion, where the chin tucks into the chest. Following flexion, the head undergoes internal rotation, where it rotates to a position where the occiput is anterior. Extension then occurs, where the head moves back to its normal anatomical position. Finally, external rotation takes place, where the head rotates to a position where the occiput is posterior. This sequence of movements allows for the safe passage of the fetus through the birth canal.

**Why Each Wrong Option is Incorrect**
**Option A:** This sequence is incorrect because extension occurs before external rotation in the correct sequence. Extension is necessary to facilitate external rotation.
**Option B:** This sequence is incorrect because external rotation occurs before expulsion in the correct sequence. External rotation is a critical movement that allows for the safe passage of the fetus, and expulsion occurs after this movement.
**Option D:** This sequence is incorrect because extension and internal rotation are in the wrong order. Extension occurs after internal rotation in the correct sequence.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the cardinal movements of labor are a sequential process that allows for the safe passage of the fetus through the birth canal. Understanding these movements is crucial for obstetricians and midwives to anticipate and manage potential complications during labor.

**✓ Correct Answer: C. Engagement-descent-flexion-internal rotation-extension-external rotation**