Answer:
C. 52,000 units.
Explanation:
Using complete and transferred:
completed and transferred   50,000
ending     10,000  3/5 =     6,000
beginning  20,000 at1/5 =    (4,000)
Equivalent units         52,000
The complete and trasnferred plus the ending ivnentory is the total units during the period, then we subtract the beginning to achieve the work for the period:
Using started and transferred:
started and trasnferred        =   30,000
work on Beg WIP 20,000 x 4/5 Â = Â Â 16,000
Ending WIP 10 x 3/5 Â Â Â Â Â Â Â Â Â Â = Â Â Â 6,000
Equivalent units                 52,000
We start and complete 30,00 then we complete the unfinished part of the beginning WIP and we had some other units at a certain level of completion
Using Units worked during the period:
Worked During the period          60,000
Unfinished of Ending 10,000 x 2/5 = Â (4,000)
B previous work   20,000 x 1/5   =  (4,000)
Equivalent units                 52,000
In total we work 60,000 units, a portion was already made, the beginning WIP
and a ortion was incomplete, the 2/5 of the ending WIP