Simple Substitution Cipher

Why
The simple substitution cipher is important because it demonstrates the simplest substitution cipher possible

What
The simple substitution cipher is a monoalphabetic cipher and as such, simply one-to-one maps each possible message in the plaintext space to a message in the cipher space as the encoding and uses the inverse mapping as the decoding function.

Vulnerabilities
The simple substitution cipher can be cracked through the cryptanalysis technique of frequency analysis

Example 1
Below is the example of a simple substitution cipher that translates messages from the plaintext space (left hand side) to the

Question: What would BED be encoded to using the above simple substitution cipher?
Answer: TPM