Answer

Tip: ‘this event’ means the event you mentioned in the question 3a!

Therefore:

Washing of the Feet – priest washes the feet of some from the congregation 

Last Supper – Special celebration Eucharist

Praying in Gethsemane – Watching in a special chapel made up to look like a garden

Betrayal/Arrest – altars stripped to show that Jesus has been left alone