Explanation: Now this question is a tricky one because all of these options are somehow involved in radioactive decay; however, in this case the SYMBOL is required NOT the elements. There are three symbols involved in radioactive decay, which are: 1. α for alpha decay 2. β for beta decay 3. γ for gamma decay
In the options only one symbol is present which is gamma. Hence option (D) Gamma ( ) is the correct answer.