Step 1: Understanding the Question:
The question asks which of the given items is not part of the initial process of {selecting} a product or service idea to pursue. It tests the understanding of the stages of new product development.
Step 2: Key Concept:
The new product development process follows a sequence of stages: Idea Generation $\rightarrow$ Idea Screening (Selection) $\rightarrow$ Concept Development & Testing $\rightarrow$ Marketing Strategy Development $\rightarrow$ Business Analysis $\rightarrow$ Product Development (Planning) $\rightarrow$ Test Marketing $\rightarrow$ Commercialization.
Step 3: Detailed Explanation:
Let's analyze the options in the context of this process:
(A) Market Assessment, (B) Practicability, (C) Competition: These three are all critical criteria used during the Idea Screening or Selection stage. Before deciding to go ahead with an idea, a company must assess if there is a market for it, if it is practical/feasible to produce, and what the competitive landscape looks like.
(D) Product Planning: This is a more detailed activity that occurs after a product idea has been selected. Product planning involves defining the product's features, design, quality level, branding, packaging, etc. It is part of the 'Product Development' stage.
Therefore, product planning is a consequence of the selection decision, not a part of the selection process itself.
Step 4: Final Answer:
Product Planning is done after selecting a product idea. Hence, it is not considered *while* selecting. Option (D) is the correct answer.