Final answer:
An 'Elderly' blood pressure cuff is not a standard size; the standard sizes are 'Pediatric,' 'Large arm adult,' and 'Thigh.'
Step-by-step explanation:
Among the options provided, the one that is not one of the three standard sizes of blood pressure cuffs is A. Elderly. The three typical sizes for blood pressure cuffs are pediatric, for small children; large arm adult, for adults with larger arms; and thigh, for measuring blood pressure on a patient's thigh. An elderly cuff is not a standard size, as blood pressure cuffs for adults typically do not vary by age. Therefore, pediatric, large arm adult, and thigh are the correct types of blood pressure cuffs.