Final answer:
The CSS exam contains 3 'deep-thinking' questions, as each one accounts for 25 points towards the total of 75 points for the exam.
Step-by-step explanation:
Based on the provided reference information, the CSS exam contains 3 questions. Each question is designed to be a 'deep-thinking' question, fostering critical thinking skills. The point system for each exam mentioned totals 75 points, with each question being worth 25 points. Therefore, when presented with the options of 35, 50, 75, or 100 questions, none of these correspond to the description in the reference material. The correct answer, based on context, must be inferred rather than directly selected from the provided choices. Hence, the exams in question have 3 'deep-thinking' questions each, contributing to the total points for the exams.