A reduction in atomic size with increase in atomic number is a characteristic of elements of Option 1) high atomic masses Option 2) $d-$ block Option 3) $f$- block Option 4) radioactive series.

As we learnt in

Atomic radii decrease with increases in atomic number from left to right but the unit of increment is very low.

- wherein

$eg\rightarrow \:\:\:58^{Ce}\Rightarrow 183\:\:pm$

$59^{Pr}\Rightarrow 182\:\:pm$

$only\:1\:pm$

f-block element shows lanthanoid contraction due to which their size decreases with increase in atomic number.

Option 1)

high atomic masses

This option is incorrect.

Option 2)

$d-$ block

This option is incorrect.

Option 3)

$f$- block

This option is correct.

Option 4)