Technology-based exploration: A student uses a spreadsheet to compute slopes to classify a quadrilateral. For points A(0,0), B(5,1), C(7,6), D(2,5), the spreadsheet shows AB parallel to CD and BC parallel to AD. It also shows diagonal slopes are negative reciprocals (perpendicular). The student claims the quadrilateral must be a rhombus. Which option correctly states (1) the conjecture supported by the exploration and (2) the conclusion that still needs a formal proof?