Por via das dúvidas, vá nos três. Não ao mesmo tempo, obviamente (a menos que sejas como São Martín de Porres e tenhas o dom da bilocação)

4/ ... participle can be found in the adjective ‘volwassen’ (adult), literally “full-grown”.

Swedish ‘vuxen’ has the same meaning, being the past participle of ‘växa’ (to grow).

And let’s not forget German ‘erwachsen’, a derivative of ‘wachsen’, its descendant of *wahsanan.

3/ ... ultimately “to grow” in general.

The original Proto-Germanic word for “to grow” is reconstructed as *wahsanan, which in English became the now rare verb ‘to wax’, as in ‘waxing moon’.

Dutch ‘wassen’, which became homophonous with the verb meaning “to wash”, is equally rare. Its past ... 3/