The correct answer is D.
OBJ-4.3: The string aGVsbG8gd29ybGQNCg== is using Base64 encoding. Base64 encoding is commonly used to convert binary data, such as ASCII text characters, into an encoded string to bypass detection mechanisms in a network. While a Base64 string won’t always end with an equal or double equal sign, it is common to see them used. This is because the equal signs are used to pad the string to the proper length and complement the final processing of the message’s encoding.