59. UART Hardware and Applications

Question.4

Bob has made the setup as shown below. However, he discovers that the communication signal over UART pins is extremely noisy. What is the most efficient solution he can implement?

Use I2C or SPI communication protocols with the slowest speed.
Use a UART repeater (e.g., an Atmega328p controller) every 10 feet.
Use voltage amplification to 9 volts for logic 1.
Use a MAX232 IC to convert the signal to RS232 protocol.