How did the building of granaries indicate that Harappan civilization was economically strong?

A-It showed that the richest Harappan citizens had excess food to trade or sell.
B-It showed that Harappa could store excess food to save, sell, or trade with others.
C-It showed that Harappa could tax farmers by taking their excess crops as payment.
D-It showed that the richest Harappan citizens were capable of planning for times of drought.

B-It showed that Harappa could store excess food to save, sell, or trade with others.

Explanation:

Harappa is a city located in modern day Pakistan.The city was notable for its excellence in agriculture and architecture. One of the most prevalent works of architecture in Harappa was the granaries. The granaries were storehouses for grains. The building of granaries was indicative of the fact that the city had excess food to save, sell, or trade with others.

The city also operated a redistributive or palace economy, where the resources generated by the populace were remitted to the central authority who would then be responsible to ensuring equitable distribution.  

not completely sure but i think it’s many moons, smaller in size and a ring system.