Permutations

10C4.
(select any 4 numbers. way of arranging them=1)
10C4 = 10*9*8*7/24 = 210

For each coin that is picked to be greater than the previous one, the basic requirement is that each of the four coins be different. So lets pick 4 coins out of 10 and arrange them in 10P4=10*9*8*7=
5040 ways.

Now, lets consider a random scenario of different numbers 1 2 3 4 which can be arranged amongst themselves in 4!=24 ways. But out of these 24 ways only 1 way i.e. 1234 is our desired outcome. So, 1 out of every 24 outcomes will be our desired outcomes. So (1/24)*5040=210 Hence B