The quality of a financial plan depends on the completeness and accuracy of client information. Debt levels, tax position, spending patterns, and cash flow capacity directly affect retirement feasibility. A planner may provide limited analysis when information is missing, but the limitation must be clearly explained and documented. Option A is professionally weak because generic assumptions can create false confidence.
Option B narrows the engagement improperly; investment recommendations cannot be separated from cash flow, tax, and debt constraints. Option D is unacceptable because undisclosed estimates can mislead the client and undermine the planning record. The correct professional response is to explain why the information is needed, request supporting documents, identify the limitations if the client still refuses, and avoid presenting unsupported conclusions as definitive. If the missing data is material, the planner may need to decline to provide a retirement feasibility opinion. References/topics: client discovery, data reliability, scope limitations, documentation.