$(4.$ BigApp Delivery Inc. had net working capital of $$300,000$ and $$140,000$ at the end of $2018$ and $201$ respectively. It had net capital spending of $$170,000$ and $$80,000,$ respectively, during $2018$ and $2019$ In $2019,$ its operating cash flow was $$200,000.$ What was its cash flow from assets in $2019?$

A$)$ $$30,000$

B$)$ $$170,000$

C$)$ $$90,000$

D$)$ $$280,000$