$(a)$ In both plants and animals,there are three phases during their life cycle.
$(b)$ In plants and animals,hormones are responsible for the transitions between these three phases.

• A
  $A$ and $B$ both correct.
• B
  $A$ and $B$ both incorrect.
• C
  $A$ is correct and $B$ is incorrect.
• D
  $A$ is incorrect and $B$ is correct.