Correct statements are
A) All Lanthanoids are more reactive than Calcium
B) ${\mathrm{Ce}}^{+4}$ is a powerful oxidizing agent and its kinetics is rapid
C) $\mathrm{Lu}{\left(\mathrm{OH}\right)}_3$is a stronger base than  $\mathrm{La}{\left(\mathrm{OH}\right)}_3$
D) Samerium is steel hard
E) ${\mathrm{IP}}_1$of early actioniods is lesser than that of early Lanthanoids
 

Initial Lanthanoids resemble ‘Ca’ and latter members resemble ‘Al’ in their reactivity;

 ${\mathrm{Ce}}^{+4}$ is a powerful oxidizing agent in Analytical chemistry because ${\mathrm{E}}_{{\mathrm{Ce}}^{+4}/{\mathrm{Ce}}^{+3}}^0$  has high positive value (1.77V) but its action is slow;
$\mathrm{La}{\left(\mathrm{OH}\right)}_3$to $\mathrm{Lu}{\left(\mathrm{OH}\right)}_3$ basic strength decreases due to decrease in ionic size and ionic character;