Which of the following scenarios is a scenario where real$-$time processing is required?

A$.$ A bank wants to aggregate the savings of all its customers across individual bank accounts to

provide this information to the tax authorities.

B$.$ Every second a flood monitoring center receives information from thousands of sensors

embedded in dikes. Unusual readings are relayed to the authorities.

C$.$ Twitter receives thousands of messages every second. Twitter wants to compute how many

messages were posted last year by all users in the US$.$

D$.$ Philae, a ESA robot probe, has just landed on the comet $67$P$.$ It sends massive amounts of data

back to earth which are used to steer the robot.

E$.$ A cloud administrator at Netflix has to be notified when a more than $1\%$ of their servers log an

abnormal amount of errors, to prevent an outage $($and thus a huge loss of money$).$

F$.$ Each Android device periodically sends usage information to Google in order to determine device

OS fragmentation $($i$.$e$.,$ what $\%$ of devices are still running Android x$.$x$?)$