Answer:
a. Metropolis
Explanation:
a. It is a metropolis because a metropolis is a city that is busy and important.
b. It is not a megacity (this answer was made via process of elimination and megacity doesn't seem like it).
c. It is not a primate city as a primate is basically something like a monkey.
d. It is not a higher-order city since higher-order cities are more distributed and are fewer in numbers.
I'm only Grade 8 this year, this answer is suggested to not be trusted