Final answer:
The radius of a water balloon with a diameter of 30 cm is 15 cm. However, this answer is not reflected in the provided options, suggesting a possible error in the question or answer choices.
Step-by-step explanation:
The question you've asked about the radius of a water balloon whose diameter is given is a basic geometry problem, which falls under the subject of mathematics. However, since the additional information provided pertains to various principles of physics such as Bernoulli's Equation, projectile motion, surface tension, and dynamics of circular motion, the subject is categorized as Physics. To find the radius of a water balloon with a diameter of 30 cm, you simply divide the diameter by 2. Therefore, the radius of the water balloon is 15 cm, which is not one of the options provided. It seems there might have been a mistake in the answer choices or the question.