Answer:
D
Step-by-step explanation:
A coin has two sides. A side tagged the head and the order side tagged the tail.
By mathematical and probabilistic standards, a fair coin is a coin which has equal value of probabilities for head turning up as well as tail turning up.
what we are saying here is that for a fair coin, P(H) = P(T) = 0.5 or 1/2
Any option or value short of this will make the coin unfair. Whenever we are having the probability of the head greater than the probability of the tail or vice versa, then the coin in question has become unfair.
Now back to the options, by observation, expressing each of the options to the smallest numbers will yield 7/10.
Let’s have a decimal value of each go drive home the point;
7/10 = 0.7
70/100 = 0.7
700/1000 = 0.7
Thus the probability of the head which is meant to be 0.5 is now given as 0.7 which shows that the coin is unfair in all three options since in the real sense they are all same numbers written in different form which of course is not the 0.5 value we should have for a fair coin for probability of getting a head
is 3 because the middle two numbers are 2 and 4, and their average is 
.