The statement suggests that the decision regarding which rocket to build lies with the National Aeronautics and Space Administration (NASA)'s technology chief. The context implies that the agency or the respective decision-makers will assess various factors, requirements, and considerations to determine the most suitable rocket design for their missions or purposes. The technology chief or relevant authorities within NASA have the responsibility and the expertise to evaluate proposed rocket designs, taking into account factors such as cost-effectiveness, technological feasibility, mission objectives, and adherence to space exploration strategies. This highlights the importance of expertise and informed decision-making in developing rockets or space vehicles to meet the scientific, exploration, and mission goals of NASA.