D is the correct answer. so lets find out how. first thing keep in mind is that the chances are not equally likely. so probability can be go like 99:1 also . so
the given data is P(2,4,6) =1/2
so P(1,3,5)= 1/2. here it does not mean P(1)=P(3). but we an surely say the sum will be 1/2.
so P(3,6)= 1/3 again sum can be 1/6 . individual probability may not be equal . so lets find the maximum probability that can exist for 5.
the maximum probability for 5 will be when there will be minimum probaility fo 1 and 3. and P(3,6) =1/3 = 0.33333. so i considered that the possible minimum probability of 3 will be 0.01. and 6 probability will be 0.32. again we get a sum of 0.333.
now one probability is already given . which is 1/6= 0.16.
minimum probability for both 3 and 1 = 0.16+0.01=0.17.
so the maximum probability for 5 will be 0.5 i.e (1/2)-0.17.
0.5-0.17= 0.33. which is equal to 1/3. ( this is the maximum probability of 5) . so we can say P({5})≤1/3
P({5})≤1/3P({5})≤1/3