The correct answer is A. speaks.
The sentence is in the present tense, so the verb “speak” should be in the present tense as well. Option B, “is speaking,” is in the present progressive tense, which is used to describe an action that is happening at the moment. Option C, “has spoken,” is in the present perfect tense, which is used to describe an action that has happened in the past but has a connection to the present. Option D, “has been speaking,” is in the present perfect progressive tense, which is used to describe an action that has been happening for some time and is still happening.
In this case, Julia is very good at languages, so she speaks four languages very well. This is a general statement about her ability, so it is in the present tense.