Sorry this wasn't clear.
The rpm carries just 'c' (as well as some small, fixed-size metadata for
interpreting it, like hash algorithm)
Just to explain that comment which suggested 'a': we have to compute the Merkle
tree at build time in order to get a root hash to sign. The Merkle tree is then fully
re-computed by the fs-verity code in the kernel for storage by the local filesystem when
the rpm is ultimately installed.