You are given a math word problem and you are supposed to make use of mathematical concepts like probability, combinatorics, linear equations, sequences/series, or simple operators like addition, subtraction, division, or multiplication to answer the given question. Choose the best option from the 5 given options and report that option.

Q: Question: In what time will a train 200 m long cross an electric pole, it its speed be 144 km/hr?

 Option A: 2 sec

 Option B: 2.7 sec

 Option C: 3.5 sec

 Option D: 5 sec

 Option E: 9.5 sec

A: Option D
****
Q: Question: A reduction of 20% in the price of salt enables a lady to obtain 10kgs more for Rs.100, find the original price per kg?

 Option A: Rs.2.9

 Option B: Rs.2.1

 Option C: Rs.2.5

 Option D: Rs.2.2

 Option E: Rs.2.7

A: Option C
****
Q: Question: A box contains nine bulbs out of which 4 are defective. If four bulbs are chosen at random, find the probability that atleast one bulb is good.

 Option A: 125/167

 Option B: 125/186

 Option C: 125/126

 Option D: 125/186

 Option E: 125/128

A:
Option C
****