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.

[EX 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
[EX A]: Option C

[EX Q]: Question: The length of a rectangular landscape is 4times its breadth. There is a playground in it whose area is 1200 square mtr & which is 1/3rd of the total landscape. What is the length of the landscape?

Option A: 100

Option B: 110

Option C: 120

Option D: 140

Option E: 150
[EX A]: Option C

[EX Q]: Question: The number of ways in which one or more balls can be selected out of 10 white, 9 green and 7 blue balls is

Option A: 892

Option B: 881

Option C: 891

Option D: 879

Option E: None of these
[EX A]:
Option D