The most complex and time-consuming type of plan is the ______.

A) business brief
B) pitch deck
C) business plan
D) feasibility study

Among the given options, the most complex and time-consuming type of plan is a detailed and comprehensive business plan. This plan requires extensive research, analysis, and preparation of financial projections, as well as a clear and concise explanation of the business concept, market analysis, marketing and sales strategies, operations plan, and management team. The other options listed are shorter and simpler plans, such as a business brief that provides a summary of the key points, a pitch deck that focuses on the value proposition and attracts investors, and a feasibility study that evaluates the viability of a new business idea.