Consumer Lag Metric in Kafka

[Madhav Ancha (BLOOMBERG/ 919 3RD A)]

Hi,

    When producerOffset is used in calculating ConsumerLag/MaxLag metric for a 
consumer, is the producerOffset 

    a) the partition offset that is visible to the clients at the leader
    b) or the partition offset that is waiting to be replicated at the leader 
please.

Thanks
Madhav.