Answer: B) Neither Kelly or Daniel is correct.Â
A geometric proof is a series of logical reasonings that, starting from a hypothesis, lead to a thesis, using a sequence of statements, axioms, and theorems.
Looking at Kelly's proof, we can say that she is not right. Indeed, she uses the thesis, what she wants to prove, as a justification for her statements.
On the contrary, Daniel uses definitions and properties as a justification for his statements. Although, he does not use the correct justification for statements 1 and 2. Indeed, ∠1 + ∠2 = 180 because they are a linear pair, as well as ∠1 and ∠4.
A linear pair is a pair of adjacent angles formed when two lines intersect, while the supplementary angles definition states that two angles are supplementary when they add to 180 degrees without being necessary next to each other. Since Daniel does not know the effective measure of the angles, he cannot use the definition of supplementary angles.
Hence, neither Kelly or Daniel is correct.