To solve this problem, we need to identify the group of animals that are both bilaterally symmetrical and acoelomate.$\newline$Let's analyze each option:$\newline \bullet$Platyhelminthes:$\newline$ - These are flatworms that exhibit bilateral symmetry.$\newline$ - They are acoelomate, meaning they do not have a body cavity (coelom).$\newline$ - Examples include planarians, flukes, and tapeworms.$\newline \bullet$Aschelminthes:$\newline$ - Also known as nematodes or roundworms.$\newline$ - They have a pseudocoelom, which is a false body cavity, not a true coelom.$\newline$ - They are bilaterally symmetrical but not acoelomate.$\newline \bullet$Annelida:$\newline$ - These are segmented worms, such as earthworms and leeches.$\newline$ - They have a true coelom (coelomate) and are bilaterally symmetrical.$\newline \bullet$Ctenophora:$\newline$ - Also known as comb jellies.$\newline$ - They exhibit radial symmetry, not bilateral symmetry.$\newline$ - They are not acoelomate.$\newline$Based on the analysis, the correct answer is Option 1: Platyhelminthes, as they are both bilaterally symmetrical and acoelomate.