Before sending data, a modem sends a request to send signal, or RTS.

ANS:A - True

RTS and CTS are the most common handshake signals. A DTE device asserts the "request to send" (RTS) signal when it is ready to receive data and desserts it when it cannot accept data. Likewise, a DCE device asserts "clear to send" (CTS) when it is ready to receive data.

RTS / CTS Flow Control is another flow control mechanism that is part of the RS232 standard. It makes use of two further pins on the RS232 connector, RTS (Request to Send) and CTS (Clear to Send). These two lines allow the receiver and the transmitter to alert each other to their state.