Final answer:
The synonymous pair of words is B. Micturition and urination, both meaning the process of expelling urine.
Step-by-step explanation:
The pair of words that are synonymous is B. Micturition and urination. These terms both refer to the process of expelling urine from the bladder. Cephalgia refers to a headache, not a stroke, which is a cerebrovascular accident. Dysphagia refers to difficulty in swallowing, not difficulty in breathing. Finally, coryza is a term for the common cold, and it's not related to the heart. In tackling this question, it is essential to have a clear understanding of medical terminology to differentiate between synonyms and unrelated terms.