= Solution
An individual is <right-censored> at $t$ when follow-up establishes that the event has not occurred through $t$, but does not reveal the subsequent event time. The observed information is $T>t$ for the continuous-time convention.
Knowing only the total number censored inside an interval does not specify the <risk sets> at the event times. For example, start with two individuals, one event and one censoring. If censoring precedes the event, the <Kaplan–Meier estimator> contributes $1-1/1=0$; if the event precedes censoring, it contributes $1-1/2=1/2$. The totals $r=2,d=1,c=1$ are identical.
Therefore \b[the timing of <right censoring> relative to the events is needed]. <Independent censoring> is also required for these changing <risk sets> to yield a valid estimate of the underlying <survivor function>.
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