Step 1: Understanding the Concept:
This question requires matching anatomical structures or biological layers with their correct descriptions or classifications.
Step 2: Detailed Explanation:
1. Option (a): Cowper's gland (bulbourethral gland) is indeed a male accessory gland. This is correct.
2. Option (b): The clitoris is a tiny finger-like structure which lies at the upper junction of the two labia minora; it is part of the female external genitalia. This is correct.
3. Option (c): The uterus has three layers. The Endometrium is the inner glandular layer, while the Myometrium is the middle thick layer of smooth muscle responsible for contractions during delivery. Therefore, this pair is incorrectly matched.
4. Option (d): The ectoderm is the outermost of the three primary germ layers in the very early embryo. This is correct.
Step 3: Final Answer
The odd one out is (c) because the Myometrium is a muscular layer, not a glandular one.