Step 1: Break down the idiom word by word.
Alpha is the first letter of the Greek alphabet; Omega is the last; together they span the complete range from first to last, representing totality.
Step 2: Trace the origin of the phrase.
The phrase appears in the Bible (Revelation 1:8) where God declares "I am the Alpha and the Omega" - meaning the beginning and the end, the source and completion of all things.
Step 3: Identify the correct meaning.
The idiom "Alpha and Omega" means the beginning and the end - the whole of something; options (1), (2), and (3) do not capture this meaning at all.
\[ \boxed{\text{Beginning and the end}} \]