A gardener wants to plant trees in his garden in such a way that the number of trees in each row should be the same. If there are 7 rows or 6 rows or 4 rows, then no tree will be left. Find the least number of trees required
Choose the correct choice from the following choices:  A) 22  B) 84  C) 28  D) 76  E) 21

Rationale: "explanation : the least number of trees that are required = lcm ( 7 , 6,4 ) = 84 . answer : b"
Answer: B