A technology leader for an instructional environment is asked to develop and present a professional development curriculum to assist other instructors who want to increase their use of technology. Specifically, they are asked to present materials to improve the use of audiovisual presentation software. What type of evaluation should the leader use to assess the development of participants' knowledge and skills as the presentation progresses? 

a. Heuristic 

b. Thematic 

c. Formative 

d. Summative