Periodic Table And Periodicity

Given below are two statements : one is labelled as Assertion \(\mathbf{A}\) and the other is labelled as Reason \(\mathbf{R}\) :

Assertion A : The first ionisation enthalpy decreases across a period.

Reason \(\mathbf{R}\) : The increasing nuclear charge outweighs the shielding across the period.

In the light of the above statements, choose the most appropriate from the options given below :