The station originating the following weather report has a field elevation of 1,300 feet msl. from the bottom of the overcast cloud layer, what is its thickness (tops of ovc are reported at 3,800 feet)?
speci kokc 2228z 28024g36kt 3/4sm bkn008 ovc020 28/23 a3000

option a
500 feet.
option b
1,700 feet.
option c
2,500 feet.