Google Ads app campaigns with conversion tracking must achieve at least $\_\_\_\_\_\_$ unique user$-$completed conversions over $30$ days for the campaign to run well. For this reason, it is important to track the "right" conversions $($e$.$g$.,$ an e$-$commerce app that sells the same dress in multiple colors should not designate each color as a separate conversion$)$ to increase the likelihood that the minimum number is met.

a$.$

$50$

b$.$

$300$

c$.$

$100$

d$.$

$75$