Final answer:
In a superheterodyne receiver, the RF amplifier and the local oscillator have their input tuned circuits tuned to the same frequency, allowing for correct signal selection and conversion to an IF for easier processing.
Step-by-step explanation:
The two stages in a superheterodyne receiver that have input tuned circuits tuned to the same frequency are the RF amplifier and the local oscillator, which corresponds to option b. This configuration is crucial for a superheterodyne receiver to function correctly, as it allows for the selection and amplification of the desired radio signal frequency. Subsequently, this selected frequency is mixed with the frequency from the local oscillator to produce an intermediate frequency (IF) that is easier to filter and amplify further in the following stages of the receiver.