At the beginning of december, global corporation had $1,400 in supplies on hand. during the month, supplies purchased amounted to $3,800, but by the end of the month the supplies balance was only $1,900. what is the appropriate month-end adjusting entry?

First calculate supplies used as follows

Beginning balance 1400
Add supplies purchase 3800
Less ending balance 1900

Supplies used
1,400+3,800−1,900=3,300

The appropriate month-end adjusting entry would be
Debit supplies expense $3300
credit supplies $3300

Hope it helps!

c. used to record an adjustment to Bad Debt Expense for the year ending December 31, 2018

Explanation:

Since the events occur after the balance sheet date, but before the balance sheet is issued, and gives more evidence about conditions that existed at the balance sheet date, then it should be used to record an adjustment to Bad Debt Expense for the year ending December 31, 2018

This is because an adjustment gives more information to the information already given in the balance sheet. Therefore, the correct option is C.