Which from following elements belongs to inner transition elements?

The inner transition elements are the f-block elements, comprising the lanthanides (atomic numbers 57–71) and actinides (atomic numbers 89–103).

Curium (Cm) has atomic number $96$, placing it among the actinides and thus within the inner transition elements. Tungsten (W, $74$), molybdenum (Mo, $42$), and ruthenium (Ru, $44$) are all d-block transition metals.

Final answer: $\boxed{A}$