Final answer:
The 3rd trimester review ultrasound examination would take the least allocated appointment time.
Step-by-step explanation:
Among the given options, the ultrasound examination that would take the least allocated appointment time is a 3rd trimester review. Ultrasound examinations in the 3rd trimester of pregnancy typically involve a quick assessment of the baby's growth, position, and overall well-being. This examination is usually shorter compared to other ultrasound examinations like cardiac referrals, a follow-up of screening for endometrial hyperplasia, or intra-operative procedures, which might require more time for detailed evaluations or procedures