Answer: Mammals and turtles
Explanation:
Mammals and turtles are more closely related to each other as compared to the other organisms.
The have the most recent common ancestors and they share common characters according to the cladogram.
Cladogram is a representation which is used to find out the closely related species. By looking into the cladogram the most recent common ancestors to mammals are reptiles.
Hence, Option A is the correct answer .