COLREGS Question

Power driven vessel 50m 4 point of your Port Bow, stbd nav light showing.
Risk of collision exists.
Action, Stand on with caution, sound 5 short blasts
Risk of collision still exists and the examiner tells you this vessel is constrained by her Draft.

Option 1
Because i have missed my early opportunity to avoid impeding her safe passage.
Sound 2 short blast and Alter course to Port.
Continue to Monitor until finally past and clear.

Option 2
Because I have missed my early opportunity to avoid impeding her safe passage.
Sound 1 short blast and alter course to starboard, parallel her course and reduce speed, to allow her to pass clear.
Continue to monitor until finally past and clear.

Under Rule 18 I am to keep out of the way of Fishing,Sailing,NUC,RAM and when complying with Rule 15 altering to Port and passing the stern is the correct action.

A vessel constrained by her Draft is not quite as straight forward as Fishing,Sail,NUC,RAM. Would I be correct if the examiner gave me a vessel constrained by her Draft from the beginning of the situation then first course of action would be to reduce speed early and allow sufficient sea room for her to pass ahead.
But in the above situation I have missed the early opportunity not to impede her passage, is it now OK to alter course to port and comply with Rule 15 ?????

Under Rule 18 why is a vessel constrained by her draft different from Fishing,Sailing,NUC,RAM and the actions required differ.
Some people say it can be treated exactly the same as Fishing,Sailing,NUC,RAM when complying with Rule 15 but there is a difference which I cant remember and I would like to know 100 percent before saying anything to a examiner.