Concept:Ionization power decreases as penetrating power increases: alpha has the highest ionization, beta is medium, and gamma is the lowest.
Explanation:Alpha particles are heavy and highly charged, so they ionize air strongly but travel only a short distance.
Beta particles are lighter and faster, so they cause less ionization than alpha but more than gamma.
Gamma rays are electromagnetic waves with no charge, so they produce the least ionization.
Therefore, for alpha, gamma, and beta in that order, the ionization powers are high, low, and medium respectively.
Answer:D. high, low, medium.