The overall increase in cash is $100. This is because debits increase cash and credits decrease cash. In this case, there are more debits than credits, so the overall increase in cash is $100.
To calculate the overall increase or decrease in cash, we subtract the total credits from the total debits. In this case, we have $16,000 in debits and $15,900 in credits. This gives us a total of $100 in debits. Therefore, the overall increase in cash is $100.
The answer is B.