How and in what quantities are actinoid elements obtained?

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: $5f$ electrons can participate in bonding to a far greater extent than $4f$ electrons.
Reason $R$: $5f$ orbitals are not as buried as $4f$ orbitals.
In the light of the above statements,choose the correct answer from the options given below:

More number of oxidation states are exhibited by the actinoids than by the lanthanoids. The main reason for this is

Number of colourless lanthanoid ions among the following is . . . . .
$Eu^{3+}, Lu^{3+}, Nd^{3+}, La^{3+}, Sm^{3+}$

Which actinoid elements have a $5f^{14}$ electronic configuration in their atoms?

Explain the lanthanoid contraction.