The most appropriate metric for assessing the success of the build activity is the quality of the product solutions, so option D is correct. Build is concerned with creating or modifying solution components so they are fit for intended use in later lifecycle stages. Measures for build therefore focus on the quality, completeness, maintainability, and suitability of what is produced. The other options are associated with different activities. Incident resolution within targets is more relevant to support. Customer satisfaction after service delivery is more relevant to deliver and service experience. First-contact fulfillment is also a service delivery or support measure. ITIL encourages organizations to choose metrics that match the purpose of each value chain activity. Since build is about producing sound product components, the quality of those solutions is the clearest measure of success.