Answer:

10

Step-by-step explanation:

Get the sum of the exponents of the three variables (c,d, and e) in each term and see which is the biggest.

8c³d²e : 3 + 2 + 1 = 6

5cd³e⁵ : 1 + 3 + 5 = 9

12c³d⁴e³ : 3 + 4 + 3 = 10