Final answer:
The type of river that carries more volume and larger size ranges of sediment than braided rivers is a single-channel river. The environment described with sand deposits and gravel is characteristic of a braided river.
Step-by-step explanation:
The student's question is about the types of sediments carried by braided rivers compared to other types of rivers. A braided river consists of a network of river channels that split and rejoin, often separated by small, temporary islands. These rivers carry more volume and a larger size range of sediments than typical single-channel rivers, which might be referred to in the sentence to be completed. Therefore, the statement could be completed as: "Braided rivers carry more volume and larger size ranges of sediment types than single-channel rivers."
When comparing two different environments described in the provided information, it's clear that option (i), which mentions "Mostly sand deposits with some sediment beds having a layer of gravel on the bottom and cross-bedding", corresponds to a braided river environment thanks to its description of sediment types that are characteristic of the high energy and dynamic nature of braided river systems.