Solution:
$\text{The relationship between pressure (P), volume (V), and temperature (T) for an ideal gas is given by the ideal gas equation:}\n\n\text{PV} = \text{nRT}\n\n\text{Where n is the number of moles and R is the ideal gas constant. For a fixed amount of gas, nR is constant, so PV is directly proportional to T.}\n\n\text{PV} \propto \text{T}\n\n\text{To determine the change in temperature, we need to analyze how the product PV changes along each path.}\n\n\text{Path A to B:}\n\text{This is an isobaric process, where pressure (P) is constant. The volume (V) increases from A to B. Since V increases and P is constant, the product PV increases. Thus, the temperature T increases.}\n\n\text{Path B to C:}\n\text{This is an isochoric process, where volume (V) is constant. The pressure (P) decreases from B to C. Since P decreases and V is constant, the product PV decreases. Thus, the temperature T decreases.}\n\n\text{Path C to D:}\n\text{This is an isobaric process, where pressure (P) is constant. The volume (V) decreases from C to D. Since V decreases and P is constant, the product PV decreases. Thus, the temperature T decreases.}\n\n\text{Path D to A:}\n\text{This is an isochoric process, where volume (V) is constant. The pressure (P) increases from D to A. Since P increases and V is constant, the product PV increases. Thus, the temperature T increases.}\n\n\text{Based on this analysis, the temperature increases as the gas goes from A to B, and also from D to A. The temperature decreases from B to C and from C to D.}\n\n\text{Let's check the given options:}\n\n\text{1. increase as it goes from A to B. (Correct)}\n\text{2. increase as it goes from B to C. (Incorrect, temperature decreases)}\n\text{3. remain constant during these changes. (Incorrect, temperature changes)}\n\text{4. decrease as it goes from D to A. (Incorrect, temperature increases)}\n\n\text{The only correct statement among the options is that the temperature increases from A to B.}$