The phenotypic sex is determined by:

Correct Answer: D

Rationale: Step-by-step rationale for why choice D is correct: 1. During early development, all embryos possess indifferent genitalia. 2. Androgen hormones, like testosterone, influence the differentiation of these structures. 3. The presence of androgen hormones leads to the development of male genitalia. 4. Lack of androgen results in the development of female genitalia. 5. This process occurs after fertilization, not during fertilization. In summary, choice D is correct as the phenotypic sex is determined by the activity of androgen hormones on the indifferent genitalia post-fertilization. Choices A and B are incorrect because sex determination occurs post-fertilization, not during fertilization. Choice C is incorrect as the SRY gene typically plays a role in sex determination but is not the primary factor influencing the phenotypic sex.

Correct Answer: B

Rationale: The correct answer is B: Clavicle and scapula. The pectoral girdle consists of the clavicle (collarbone) and the scapula (shoulder blade). The clavicle articulates with the sternum, providing a connection between the upper limb and the axial skeleton. The scapula forms the shoulder joint with the humerus. The sternum is part of the axial skeleton and not directly part of the pectoral girdle. The humerus is a bone of the upper arm and not part of the pectoral girdle. Therefore, the correct answer is B as it accurately represents the bones that make up the pectoral girdle.

Correct Answer: B

Rationale: The correct answer is B: Cribriform plate. The olfactory nerves pass through the cribriform plate, which is a part of the ethmoid bone located in the anterior cranial fossa. This structure contains numerous small perforations that allow the olfactory nerve fibers to pass through and enter the cranial cavity, specifically the olfactory bulb. The other choices, A, C, and D, are incorrect because the foramen ovale is located in the sphenoid bone and transmits the mandibular nerve, the foramen spinosum transmits the middle meningeal artery, and the superior orbital fissure transmits structures like the oculomotor nerve, trochlear nerve, and ophthalmic nerve, but not the olfactory nerves.

Correct Answer: D

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.

Correct Answer: A

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.