Answer:
B. active volcanoes
Step-by-step explanation:
Mexico City is located close to a volcano called Popocatepetl that is 70 km southeast of the city and it is the most active volcano in Mexico. Also, San Salvador has a volcano called Santa Ana that is located 45 km west of the city and it is one of the most active volcanoes in El Salvador. So, according to that, the answer is that Mexico City and San Salvador are both adjacent to active volcanoes.