To solve this problem, we need to analyze each statement regarding the classification of different animal phyla:$\newline \bullet$Statement A: Annelids are true coelomates.$\newline$ - Annelids, such as earthworms, have a true coelom, which is a body cavity completely lined with mesoderm.$\newline$ - Therefore, this statement is correct.$\newline \bullet$Statement B: Poriferans are pseudocoelomates.$\newline$ - Poriferans, or sponges, do not have a coelom or body cavity. They are simple organisms with a porous body.$\newline$ - Therefore, this statement is incorrect.$\newline \bullet$Statement C: Aschelminthes are acoelomates.$\newline$ - Aschelminthes, also known as nematodes or roundworms, have a pseudocoelom, which is a body cavity not completely lined with mesoderm.$\newline$ - Therefore, this statement is incorrect.$\newline \bullet$Statement D: Platyhelminthes are pseudocoelomates.$\newline$ - Platyhelminthes, or flatworms, are acoelomates, meaning they lack a body cavity.$\newline$ - Therefore, this statement is incorrect.$\newline$Based on the analysis, only Statement A is correct.$\newline$Therefore, the correct answer is Option 4: Only A.