In the introduction to K&R there is the following text:Similarly, C offers only straightforward, single-thread control flow:  tests, loops, grouping, and subprograms, but not multiprogramming,  parallel operations, synchronization, or coroutines.What does grouping refer to? It is not in the index, and searches have been unfruitful so far. I've programmed some C (though I'm far from an expert), and haven't heard the term before.
What is grouping?
c
C program source text is free-format, using the semicolon as a statement terminator and curly braces for grouping blocks of statements. (Wikipedia) Blocks don't look like control flow, but they are; without the curly braces only the next line would be controlled by a loop keyword, but with the braces the entire block is looped over.