Answer:
The correct answer is b. the transition to bipedalism
Step-by-step explanation:
Bipedalism is the type of movement or locomotion in which any animal use their two legs to move. A squirrel do not have ability to do transition to bipedalism but hominids like monkey have the ability to walk and run on two legs. So this transition from squirrel to a monkey can easily be seen.
Bipedalism allow monkeys to use their arms for different purpose like hanging on trees, making or using tools, fighting, using their hands to communicate each other and show their emotions. Reports shows that bipedalism require less energy for locomotion showing their advantage.