Step 1: Analyze Locomotion Types in Protozoa:
Pseudopodia: Amoeboid movement (e.g., \textit{Amoeba}).
Flagella: Flagellar movement (e.g., \textit{Euglena}).
Cilia: Ciliary movement (e.g., \textit{Paramecium}).
Gliding/Metaboly: Seen in Sporozoans (e.g., \textit{Monocystis}, \textit{Plasmodium} sporozoites) and some flagellates. This movement is often attributed to contractile fibrils in the pellicle or cortex.
Step 2: Identify the Organelle:
The contractile fibrils responsible for body contraction and gliding/wriggling movements (gregarine movement) in these organisms are called **Myonemes**.
Step 3: Final Answer:
Option (A) is the correct effector for gliding/metabolic movement in this context.