$16 \cdot 1$ Given $n$ points on a plane, it is known that $1, 2, 4, 8, 16, 32$ are all distances between some pairs of these points. Then, the minimum possible value of the number of points $n$ is
(A) 4 .
(B) 5 .
(C) 6 .
(D) 7 .
(China Junior High School Mathematics League, 1997)
［Solution］Since no three of the above distances can form the three sides of the same triangle, the distribution of these points and distances can only be as shown in the right figure, in other words, there must be at least 7 points.
Therefore, the answer is $(D)$.