The phrase "because of" is a prepositional phrase used before a noun phrase (her good work) to indicate the cause. "Because" is a conjunction and must be followed by a full clause (subject + verb).

১. Since "her good work" is a noun phrase, using the conjunction "because" would be grammatically incorrect.
২. "Since" and "as" also function as conjunctions here and require a clause to complete the sense.
৩. "Because of" correctly links the result (succeeded) with the reason (good work).

অতিরিক্ত তথ্য: In English grammar, "due to" or "owing to" can sometimes be used similarly to "because of".