How many combinations of three letters taken from letters (a, a, b, b, c, c ) are possible?
Options:
A) 12
B) 13
C) 5
D) 7
E) 6
So 3C3 for abc - 1 choice   2 more for aa(b,c )   2 more for bb(a,c )   2 more for cc(a,b )   total 7   Ans :7
<result>D</result>
How many combinations of three letters taken from letters (a, a, b, b, c, c ) are possible?