Final answer:
The test known as that involves an x-ray of the bladder and urethra done while the child is urinating is called a Voiding cystourethrogram (option a).
Step-by-step explanation:
The test known as that involves an x-ray of the bladder and urethra done while the child is urinating is called a Voiding cystourethrogram (option a). This test helps to evaluate the anatomy and function of the bladder and urethra during urination. It is commonly used to diagnose conditions such as vesicoureteral reflux, urethral obstruction, or urinary incontinence.