Final answer:
El Chichón Volcano was dormant for about 550 years before its 1982 eruption, making the correct answer D) 550 years.
Step-by-step explanation:
The El Chichón Volcano had been dormant for a significant amount of time before its notorious 1982 eruption. According to geological studies and historical records, the volcano was dormant for about 550 years prior to this event. Dormancy in volcanology refers to a period during which a volcano does not exhibit any eruptive activity.
When considering the options provided in the question, the correct choice would be D) 550 years. This long period of inactivity likely contributed to the lack of preparedness for the eruption, as the possibility of an event would have seemed quite remote to the local population and authorities.