Consider the following pairs:
$$\begin{array}{cc}\text{Tributary}& \text{Main River}\\ \text{(a) Chambal}& \text{Narmada}\\ \text{(b) Son}& \text{Yamuna}\\ \text{(c) Manas}& \text{Brahmaputra}\end{array}$$

Which of the pairs given above is/are correctly matched?

Let us analyze each pair individually:
* (a) Chambal: It is a principal tributary of the Yamuna River, flowing through Madhya Pradesh and Rajasthan, not the Narmada River.
* (b) Son: It is a major southern tributary of the Ganga River, originating near Amarkantak, not the Yamuna River.
* (c) Manas: It is a transboundary river in the foothills of Bhutan and India, and is a major right-bank tributary of the Brahmaputra River.
Therefore, only pair (c) is correctly matched.