Answer:
David is studying giraffe.
Step-by-step explanation:
David is studying a mammal, but Ping is not.
The animal that Mandy is studying can be found in the ocean.
The animal that Alan is studying is slower than the animal that David is studying.
a. Dolphin - This is an aquatic animal that Mandy could be studying, so we can be sure that David is not studying this.
b. Elephant - This is a mammal but slower than giraffe so, Alan is studying this.
c. Sailfish - This is aquatic animal so, David is not studying.
d. Giraffe - This is faster than Elephant, so David is studying this animal.
