Explanation

(d)
Here, two numbers are selected from {1,2,3,4,5,6,}
$\Rightarrow n(S) = 6 \times 5\${as one by one without replacement}
Favourable cases,
[table] First number | Possible value for second number ; 1 | 2, 3, 4, 5, 6 ; 2 | 3, 4, 5, 6 ; 3 | 4, 5, 6 [/table]
There are 12 ways but the numbers may be interchanged
$\therefore\ n(E) = 2 \times 12 = 24$
$\therefore$ Required probability$= \frac{n(E)}{n(S)} = \frac{24}{30} = \frac{4}{5}$