Answer: C. The fledgling business, though small was doing quite well.
Step-by-step explanation:
The sentences that contains the correct usage of the commas include:
• Zeke, in fact, beat his old record in the breaststroke by almost two seconds.
• Cats, like other seemingly harmless animals, can cause a lot of harm with their claws.
The incorrect usage of the comma can be found in option C which is "The fledgling business, though small was doing quite well".
It should have been correctly written as " The fledgling business, though small, was doing quite well".