An element X has a mass number of 4 and atomic number 2. Write the valency of this element. Will it react with other atoms of different elements? Give a Reason.
A. Valency: 2, Yes, it will react.
B. Valency: 1, No, it will not react.
C. Valency: 2, No, it will not react.
D. Valency: 1, Yes, it will react.