For points a, b, and c, ab = 2, bc = 3, and ac = 4. select one: a. a, b, and c are noncollinear. b. a, b, and c form a right triangle. c. a, b, and c are collinear. d. a, b, and c form an equilateral triangle.

Short A
Remark
C
Let's start with the false choices.
If they were colinear, then if AB + BC would = 5 or 1 depending on the location of C.   Answer C is not correct.

B
a b and c do not form a right triangle. a^2 + b^2 ≠ c^2
2^2 + 3^2 = 13 not 16 (which is what c^2 or 4^2 = )

D 
D is false. Equilateral triangles have 3 equal sides. 

A is true. Since A and C are opposites and you have eliminated C by arguing A. Then A must be the  answer.

Um what? rephrase that ?