The mass spectrum of element Y shows three singly charged peaks with the following m/z values and relative intensities:
• 24.0 (intensity 5)
• 25.0 (intensity 10)
• 26.0 (intensity 85)
Which of the following is closest to the average atomic mass of element Y?
a) 25.3 amu
b) 25.0 amu
c) 25.8 amu
d) 24.2 amu