How many 234-9028 air fuel oxygen sensors are there in 2002 Toyota Rav4 please?

One>: Upstream sensor (located before catalytic converter) Notes: " PASSENGER/RIGHT SIDE ". SEE rockauto.com for best price,compared to local rip off part stores for exact same part#,Denso 234-9028.... https://www.rockauto.com/en/catalog/toyota,2002,rav4,2.0l+l4, 1388910,exhaust+&+emission,oxygen+(o2)+sensor,5132