Which means of transport are safest?
The Swiss Foreign Ministry recommends using only official or booked taxis plus the metro and metro buses in Rio, which are considered relatively safe. At night, the German Foreign Office recommends taxis over public transport. At the airport, book and pay for your taxi inside the terminal.
Source: https://www.eda.admin.ch/countries/brazil/de/home/reisehinweise/vor-ort.html ; https://www.auswaertiges-amt.de/de/service/laender/brasilien-node/brasiliensicherheit-201092