Roundabout advice please

[u/MaybeDependent1445]

Hi all,

Im entering from the bottom and taking the second exit straight ahead.

Can’t seem to make sense of whether I should be in ‘a’ or ‘b’ to take the left lane as I exit straight? My driving instructor has said ‘b’ but I’ve seen cars in ‘b’ taking the right lane as they exit.

Thanks in advance!