So this that will have a negative charge as well, because eleven is above the PKA of this side chain group. And so if we sum up these charges, 1234 negative charges. And so that means we have full charge, or not a full charge, but a net charge of negative four. Okay? So out of all these cases seized, only one that can be used to find our pi value. Remember, to find the isoelectric point, the pi, we want to estimate the PH at which the net charge on a protein would be zero, which is choice C. So now we want to use this PH of seven to basically find what the average of the two PK values is above and directly below the PH of seven.