**Core Concept:** Contraindications in obstetrics refer to situations where the use of a particular medication, procedure, or intervention is not recommended due to potential risks for the mother or the fetus. In the context of the question, we are discussing drugs and their contraindications during labor stages.

**Why the Correct Answer is Right:**

Drug A (Option C) is a case of a drug contraindicated in the 1st and 2nd stages of labor. Secobarbital sodium is a barbiturate sedative-hypnotic medication with sedative, hypnotic, and anxiolytic properties. During labor, it can cause respiratory depression, hypotension, bradycardia, and decreased uterine contractions, which can lead to maternal and fetal complications.

Drug B (Option D) is another example of a drug contraindicated during labor. Codeine is a weak opioid analgesic used for pain relief. In labor, it can cause respiratory depression and hypotension, which can be detrimental to both the mother and the fetus.

Drug C (Option A) is a case of a drug contraindicated during labor. Cyclopentolate is a cycloplegic drug used to dilate the pupil for examination. Its use during labor can lead to maternal and fetal hypotension, bradycardia, and respiratory depression, resulting in potential complications.

Drug E (Option B) is a drug that is generally safe during labor, though it should be used judiciously. Ergotamine is a vasoconstrictor used for the treatment of migraine and uterine spasms. However, if used during labor, it can cause uterine hyperstimulation, tachysystole, and increased risk of preterm labor.

**Why Each Wrong Answer is Incorrect:**

Option A (Cyclopentolate) and Option E (Ergotamine) are incorrect because they are contraindicated or carry significant risks during labor.

Option B (Codeine) is incorrect as it is also contraindicated during labor due to respiratory depression and hypotension.

Option C (Secobarbital) is incorrect as it is contraindicated during labor due to respiratory depression, hypotension, and bradycardia.

**Clinical Pearl:**

Caution should be exercised when administering medications during labor. While some medications may be safe or beneficial, others can lead to severe complications for both the mother and fetus. Always consider the potential risks and benefits of each medication before administering it to a patient in labor.