Multiple choice How many distinct binary search trees can be created out of 4 distinct keys? 5 14 24 42 Reveal answer Fill a bubble to check yourself B Correct answer Explanation The number of distinct binary search trees with n nodes is given by the nth Catalan number: C(n) = (1/(n+1)) * binom(2n, n). For n=4, C(4) = (1/5) * binom(8, 4) = (1/5) * 70 = 14.