we know that
The least common multiple is the smallest positive number that is a multiple of two or more numbers
case A)30,90,390
30-------> 2.3*5
90------> 2*3²*5
390---> 2*3*5*13
the LCM is----> 2*3²*5*13----> 1170
case B)18,30,54
18----> 2*3²
30----> 2*3*5
54----> 2*3³
the LCM is -----> 2*3³*5----> 270
case C)25,125,120
25----> 5²
125---> 5³
120---> 2³*3*5
the LCM is----> 5³*2²*3----> 1500
case D)2,9,15
2----> 2
9----> 3²
15---> 3*5
the LCM is ----> 2*3²*5----> 90
the answer is the option
B)18,30,54