The child became slippery in Andrew's hand because of constant juggling between waters.

Explanation:
When we analyze the given options, it becomes clear that the child becoming slippery in Andrew's hand cannot be attributed to the atmosphere in the room or Andrew losing his focus. Thus, the correct answer is option 'C' - because of constant juggling between waters.

Constant juggling between waters:
Juggling between waters refers to the act of regularly switching between handling and carrying different containers or bodies of water. In the context of the question, Andrew was likely trying to hold multiple containers or bodies of water simultaneously, causing the child to become slippery.

Effects of constant juggling:
1. Wet hands: Handling water containers or bodies of water can make the hands wet. Wet hands tend to reduce friction, making it easier for objects to slip out of one's grasp. In this case, the child became slippery due to Andrew's wet hands caused by the constant juggling between waters.

2. Reduced grip: Constantly switching between water containers may lead to fatigue in the hands and muscles involved in gripping. Fatigue can weaken the grip strength, making it more challenging to hold onto objects securely. As a result, the child may have slipped from Andrew's hand due to his reduced grip caused by the continuous juggling.

3. Slippery surfaces: When handling multiple water containers, there is a possibility of water spilling or splashing onto the surrounding surfaces. These wet surfaces can become slippery, making it difficult to maintain a firm grip on objects. If Andrew's hand came into contact with a wet surface, it could have contributed to the child becoming slippery in his hand.

Conclusion:
Constantly juggling between waters can lead to wet hands, reduced grip strength, and slippery surfaces. All these factors combined could have caused the child to become slippery in Andrew's hand.