Which quartz sample has probably undergone abrasion in a stream for the longest period of time?

1)A
2)B
3)C
4)D

Conclusion: m∠spt + m∠tpu = 90° which of the statements supports the conclusion from the diagram and the given information. vertical angles are equal in measure. perpendicular lines meet to form right angles. adjacent angles whose exterior sides are perpendicular rays are complementary. adjacent angles whose exterior sides are perpendicular rays are supplementary.