Find out whether there is any grammatical error in below sentence.In management, as you rise higher, / the problems you face become more and more unstructured and you can't just fall back on / the tools you had been

• A. the tools you had been
• B. No error
• C. In management, as you rise higher,
• D. the problems you face become more and more unstructured and you can't just fall back on

Answer: (D)