Answer: 
Explanation:
General representation of an element is given as: 
where,
Z represents Atomic number
A represents Mass number
X represents the symbol of an element
Beta decay : In this process, a neutron gets converted into a proton and an electron releasing a beta-particle. The beta particle released carries a charge of -1 units.

The given reaction would be represented as:

Answer:
the correctanswer is a a and b
First cell theory. All living things are composed of cells.
Second cell theory. Cells are the basic unit of structure and function in living things.
Third cell theory. All cells are produced from other cells