Assertion `(A): ` The emission of `alpha-` particles results in the formation of isodiapher of parent element.
Reason `(R) : ` Isodiaphers have same isotopic number.
A. If both `(A)` and `(R)` are correct , and `(R)` is the correct explanation of `(A)`
B. If both `(A)` and `(R)` are correct, but (R) is not the correct explanation of `(A)`
C. If `(A)` is correct, but `(R)` is incorrect.
D.