A 0.465 kg iron horseshoe that is initially at 540°C is dropped into a bucket containing 19.8 kg of water at 21.0°C. What is the final equilibrium temperature (in °C)? Neglect any heat transfer to or from the surroundings. (Use 448 J/kg·°C for the specific heat of iron and 4,184 J/kg·°C for the specific heat of water.)
A. 25.5
B. 28.3
C. 31.2
D. 33.8