the engineering team analyzed four potential designs, all calculated using an 18.0 v dc power source and 2.0…

Answer:

The design with the lowest total resistance will produce the most heat (wattage). In a parallel - circuit, the more resistors in parallel, the lower the total resistance. Assuming the second design has more resistors in parallel compared to the others (since the image shows different configurations and parallel - connected resistors reduce total resistance), the design with the most resistors in parallel will produce the most heat. Without seeing all four designs clearly, in general, for a fixed voltage source $V = 18.0$ V and resistors of $R=2.0$ - ohm each, the power formula is $P=\frac{V^{2}}{R_{total}}$. So the design with the smallest $R_{total}$ will have the highest power (wattage). If we assume the second design has the most resistors in parallel, it will have the lowest $R_{total}$ and thus produce the most heat.

Explanation:

Step1: Recall power formula

$P=\frac{V^{2}}{R_{total}}$

Step2: Analyze effect of resistance on power

For fixed $V$, lower $R_{total}$ means higher $P$.

Step3: Understand parallel - resistor effect

More resistors in parallel lower $R_{total}$.