What is the general electronic configuration of actinoids?

Given below are two statements:
Statement $I$: In the Lanthanoids,the formation of $Ce^{+4}$ is favoured by its noble gas configuration.
Statement $II$: $Ce^{+4}$ is a strong oxidant reverting to the common $+3$ state.
In the light of the above statements,choose the most appropriate answer from the options given below:

The common oxidation state of the elements of the lanthanoid series is .....

The outer electronic structure of lawrencium (atomic number $103$) is

The most common lanthanide is

The percentage $(\%)$ of iron in pyrophoric mischmetal is ...........