Assertion $(A)$: In mosses,vegetative reproduction occurs through fragmentation and budding.
Reason $(R)$: The spore-producing sporophyte stage in mosses is responsible for asexual reproduction.

• A
  $A$ and $R$ are both true,and $R$ is the correct explanation of $A$.
• B
  $A$ and $R$ are both true,but $R$ is not the correct explanation of $A$.
• C
  $A$ is true,but $R$ is false.
• D
  $A$ is false,but $R$ is true.