Work is in units of Jules, so any comparison with time is incorrect. Answer D is the definition for velocity, which is incorrect. Answer C is the correct answer
Light. The black hole is a vacuum, and not even light can escape it's suction
Answer: Scientists observe natural events occuring around them. If a hypothesis is not veriffied by the results from the scientific method, scientists may redo the process or create a new hypothesis
Explanation:
When light travels from a medium with higher refractive index to a medium with lower refractive index, there is a critical angle after which all the light is reflected (so, there is no refraction).
The value of this critical angle can be derived by Snell's law, and it is equal to

where n2 is the refractive index of the second medium and n1 is the refractive index of the first medium.
In our problem, n1=1.47 and n2=1.33, so the critical angle is