Explanation:
Given that,
The mass of rock, m = 2.35-kg
It was released from rest at a height of 21.4 m.
(a) The kinetic energy is given by : 
As the rock was at rest initially, it means, its kinetic energy is equal to 0.
(b) The gravitational potential energy is given by : 
It can be calculated as :
(c) The mechanical energy is equal to the sum of kinetic and potential energy such that,
M = 0 J + 492.84 J
M = 492.84 J
Hence, this is the required solution.
Answer : Option C) Detective Smiley scanned the dim hallway. He pulled his pistol from its holster.
Explanation : Amongst the given other choices there seems to be no relationship between two consecutive sentences. The only sentence which seemed to have a connection between previous and later sentence was option C. Where it is clearly stated that the detective named as Smiley was walking through the hallway which was dimly lit. The second sentence has a co-relation to the previous one as it extends the sentence. Detective smiley then pulled out his pistol from his holster after walking through the hallway.
This confirms that the correct answer for this question is Option C.
