A very intense start is a bright star at very high temperature. Now, hotter the object shorter is the wavelength of peak radiation. The increasing order of wavelength of the given regions in the electromagnetic spectrum are:
gamma range < ultra violet < visible < infrared
Ideally, since the shortest wavelength based on the given options is the gamma range, the peak intensity can also be expected to fall at that wavelength. If the star spectrum was recorded in the UV-visible range of the EM spectrum, then it would fall in the UV range
Sodium is a very reactive metal, it tends to react with oxygen to form sodium oxide but this is an unstable compound and soon reacts with hydrogen to form sodium hydroxide. Sodium is the metal reacts vigorously with oxygen and water.
