The root phon, meaning "sound," indicates that the word symphony most likely means

"a large meal."
"a beautiful view."
"a musical concert."
"a fragrant bouquet."

The Word "Symphony comes from the Latin symphonia "a unison of sounds.

It is divided as such: from the assimilated form from the Greek of syn- "together"  + phone "voice, sound,". Put more simply:

Syn: "together"+ phone: sound= sound put together

So, to give this question a final answer, the word symphony most likely means:

"a musical concert."

answer: do

the 'italicized phrase' is a noun clause that is used as a direct object.

because they were not just any seashells they were sally's seashells