The correct answer is A. 1800 units.
To calculate the equivalent units of work done in the current period, we need to add the beginning work-in-process equivalent units to the work done in the current period equivalent units, and subtract the ending work-in-process equivalent units.
Therefore, the equivalent units of work done in the current period are 2500 + 3800 – 5000 = 1800 units.
Option B is incorrect because it is the equivalent units of work done in the current period plus the ending work-in-process equivalent units.
Option C is incorrect because it is the equivalent units of work done in the current period minus the beginning work-in-process equivalent units.
Option D is incorrect because it is the beginning work-in-process equivalent units.