Final answer:
A star that is the same size as the Sun but five times hotter emits the most infrared radiation due to its higher temperature, which results in more power radiated at all wavelengths, including infrared.
Step-by-step explanation:
The object that emits the most infrared radiation among the ones listed would be c. a star that is the same size as the sun but is five times hotter. Considering the principles of radiation and temperature, the amount and type of electromagnetic radiation emitted by dense astronomical objects like the Sun and other stars are primarily determined by their temperature. An essential aspect from physics states that an object at a higher temperature emits more power at all wavelengths compared to a cooler object. Therefore, a star with a temperature much higher than the Sun's will emit significantly more energy across the spectrum, which includes a substantial increase in infrared radiation.
For example, the Sun, radiating at a surface temperature of about 6000 K, emits roughly half of its energy in the infrared region. However, a star that is five times hotter will see an increase in infrared radiation output due to its significantly higher temperature. This is in accordance with the Stefan-Boltzmann law, which states that the power radiated by a blackbody is proportional to the fourth power of its absolute temperature, suggesting that even a small increase in temperature can result in a large increase in radiation emitted.