The four sentences labelled A, B, C and D, given below in jumbled order, together form a coherent paragraph. Arrange the sentences in the most logical order and choose the sequence that produces the best paragraph.

A. As a result, even roadside vegetable sellers now display printed QR codes beside their weighing scales.
B. A decade ago, most shopkeepers in India's small towns dealt strictly in cash.
C. The turning point came when mobile data plans became cheap enough for almost every phone owner.
D. Affordable data allowed payment apps to reach customers who had never owned a debit card.