Explanation

The word "Level" in itself is not an onomatopoeia or a verb like "was leaving."

Among the given options, "parallel" is the most relevant choice because:

"Level" can mean even, flat, or parallel to a surface.

It is not synonymous in itself (though it has synonyms).

It is not an onomatopoeia (a word that mimics sound).

"Was leaving" is a verb phrase, while "Level" is usually a noun, verb, or adjective.