Final answer:
The population of Mexico City, according to data from 2010, was officially about 18 million, but unofficial estimates can reach 30 million, making option A) 22 million the closest answer.
Step-by-step explanation:
The population of Mexico City is a significant and complex topic, given that the city is one of the largest in the world. According to information available from 2010, the official population was about 18 million, while unofficial estimates, considering the numerous slums, may reach up to 30 million. Considering this, the option closest to the authoritative figures is A) 22 million, as B) 15 million seems too low, C) 5 million is definitely too low, and D) 60 million is far too high. Nonetheless, these figures can fluctuate due to the high birth rates, migration, and the fact that the actual population may not be exact due to the informal settlements around the city.