Research (BMC)

Research is the necessary action required for unlocking upgrades in Bloons Monkey City and Bloons Monkey City Mobile. They cost City Cash, and sometimes Bloonstones, and must be researched in an Upgrades Building, with the order of tiers. The lowest tier is researched before the highest in a certain path of a certain tower.

Table of research (Maybe rename this title?)
Note that in BMC Flash, researching tier-3 upgrades costs a sum of City Cash plus 20, while researching tier-4 upgrades costs a sum of City Cash plus 50.

(insert the whole table of all towers and all of their upgrade costs here, with the upgrade building costs as well)