Step 1: Read the flow direction next to each plate.
The figure shows fluid moving upward next to plate 1 and downward next to plate 2, with the two branches meeting near the middle of the gap.
An up-one-side, down-the-other pattern is the standard natural convection loop that forms inside a vertical enclosure.
Step 2: Link the direction of motion to buoyancy.
Fluid rises where it gets heated and becomes lighter than its surroundings, and it sinks where it gets cooled and becomes heavier.
Since fluid rises next to plate 1, plate 1 must be hotter than the bulk fluid, so \( T_1 > T_3 \).
Since fluid sinks next to plate 2, plate 2 must be cooler than the bulk fluid, so \( T_3 > T_2 \).
Final Answer:
Combining both relations gives \( T_1 > T_3 \) and \( T_3 > T_2 \), which is option (A).
\[ \boxed{T_1 > T_3 > T_2} \]