Which of the following species has the lowest ionization potential?

Which of the following elements has the highest ionisation energy?

The first ionisation potential will be maximum for

In which of the following arrangements,the order is $NOT$ according to the property indicated against it?

Which of the following has the highest first ionisation energy?

Given below are two statements. One is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: The first ionization enthalpy for oxygen is lower than that of nitrogen.
Reason $R$: The four electrons in $2p$ orbitals of oxygen experience more electron-electron repulsion.
In the light of the above statements,choose the correct answer from the options given below.