Correct Answer:  C

Explanation:

Since, numbers are consecutiveSo, for the case of calculation,

Let, a = 1b = 2c = 3d = 4e = 5

Sum of this five numbers= l +2+3 +4+5= 15

After deleting one of the five numbers sum of the remaining number = 80% of 15=15$\times \frac{80}{100}$=12

The sum decreased = 15 – 12 = 3. Which is equal to C.C was deleted from a. b. c, d & e.

Alternative Solution:Let, a = 1b = 2c = 3d = 4e = 5

Sum = a + b + c + d+ e = 5x +10 = 5(x +2) ———— (i)

Since, deleting one number of the above the sum in decreased by 20%

So, the value of the number will be the 20% of the sum of number.

Deleted number = 20% of sum=$\frac{1}{5}\times 5$(x+2) [20%=$\frac{1}{5}$ and formula ….(i) ]

=x+2=C  [ we let, c = x+2]