The figure below illustrates pair production in the early universe, with one particle labeled with a question mark.What type of particle must this be? 
Definitions:
Input-Related
Pertains to factors, resources, or materials that are required for the production process or service delivery.
Sales Objective
A specific goal set by a business or sales team aimed at increasing the quantity or quality of sales over a certain period.
Salesforce Evaluation
The process of analyzing and assessing the performance and effectiveness of a company's sales force and implementing improvements based on the assessment.
Sales Management Process
A systematic approach involving strategies, techniques, and tools to drive sales efficiency and achieve business revenue targets.
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