Assertion: the `4f^(-)` and `5f^(-)` inner transition series of elements are placed separately at the bottom of the modern periodic table.
Reason : (i) Position of f-block elements prevents the undue expansion of the mordern periodic table, ie, maintains its structure.
(ii) Position of f-block elements preserves the principle of classification by keeping elements with similar properties in a single column.
A. If both assertion and reason are true and reason is the correct explanation of assertion
B. If the assertion and reason are true but reason is not the correct explanation of assertion.
C. If assertion is true but reason is false.
D. If assertion is false but reason is true.
