Wien's law relates the temperature and the peak wavelength of radiation.
It states that Peak wavelength of radiation is inversely proportional to the temperature of the radiation.
1. This means a very hot O type star would emit shorter wavelength radiation. Thus, a very hot, type O star would most likely emit its most intense radiation as Ultraviolet. Ultraviolet radiation has smaller wavelength as compared to other given radiation.
2. A wavelength of 1000 nm corresponds to infrared radiation. Infrared radiation have spectral band from 750 nm to 1000 nm. The peak intensity of radiation for a particular star occurs at a wavelength of 1,000 nm. Thus, it lies in infrared spectral band.
3. From Wien's displacement law:

A star has a surface temperature of 30,000 K. Thus, the peak radiation would occur at 97 nm.