With a long string of bits representing a message encoded as ASCII characters (e.g. 101010101010111101....), how do we k

[answerhappygod]

With a long string of bits representing a message encoded as
ASCII characters (e.g. 101010101010111101....), how do we know
where one character starts and one ends?
Question 3 options:
The number of bits for each character is fixed. (Usually 8 bits
per character)
Characters begin with a 1
Characters begin with a 0
There is a space between the end of one character and the start
of another.