Can I install a Honeywell WIFI Thermostat?
The C wire, not to be confused with R or RC is the return path. Think of it as a ground, though technically not. Based on the information above, none of the wires O, B, W, G, R, Y, will work for C.  So they can not be jumped over to the C connection.  The C wire, usually the brown wire on the transformer, the low voltage (24v) is the common. However, no matter the color, there are only two low voltage wires on the transformer, one power (Red, Blk, Yel), one common.  So what ever color not representing the power, is the common C.  Of course, AC current flows both directions, but trying to make this simple.  Anyway, that wire (the non power wire) needs to come in to the thermostat for the C connection. With an extra wire (any color on the wire loom at the thermostat can be traced back to the 24v transformer and connected to the common, usually color brown wire). That extra wire used, the new color will become the C wire. Just a note, one issue I have had with the WiFi thermostat is the fan ON and Auto don't work independently. So for example, if the thermostat is selected to run the fan ON - no cooling or heating, I've seen that not work. It can be fixed too, just not answering that.