1. **State the problem:** Calculate the total cost for 25 students and 4 adults (1 teacher + 3 parents) to enter the museum. 2. **Identify the costs:** - Student admission: $3.50 each - Adult admission: $5.00 each 3. **Calculate the total number of adults:** $$1 + 3 = 4$$ 4. **Calculate total cost for students:** $$25 \times 3.50 = 87.50$$ 5. **Calculate total cost for adults:** $$4 \times 5.00 = 20.00$$ 6. **Calculate total cost for all:** $$87.50 + 20.00 = 107.50$$ 7. **Answer:** The total cost for all students and adults to enter the museum is **107.50**. Therefore, the correct choice is **D. 107.50**.