To find the speed in m/s, first calculate the speed in km/h. Speed is defined as distance divided by time. Given Distance = 162 km, Time = 3 hours. So, Speed = $162 \text{ km} / 3 \text{ hours} = 54 \text{ km/h}$. Next, convert km/h to m/s. We know that $1 \text{ km} = 1000 \text{ m}$ and $1 \text{ hour} = 3600 \text{ s}$. So, $1 \text{ km/h} = (1000 \text{ m}) / (3600 \text{ s}) = 5/18 \text{ m/s}$. Therefore, $54 \text{ km/h} = 54 \times (5/18) \text{ m/s} = 3 \times 5 \text{ m/s} = 15 \text{ m/s}$. Options B, C, and D are incorrect as they result from incorrect unit conversions or calculations.