Beatrice was unable to concentrate on her project because her brother’s stereo was turned up to full volume.

which statement is correct?

a comma is needed in this sentence before the word "because" to separate the dependent clause from the independent clause.
the phrase "on her project" should be separated from the rest of the sentence by commas on both sides.
the dependent clause follows the independent clause in this sentence, so no comma is needed.
this is a compound sentence made up of two independent clauses, so no comma is needed.

this is a compound sentence made up of two independent clauses, so no comma is needed.

glamis thou art, and cawdor; and shalt be what thou art promis'd; yet do i fear thy nature; it is too full o' the milk of human kindness to catch the nearest way: thou wouldst be great; art not without ambition; but without the illness should attend it. what thou wouldst highly, that wouldst thou holily; wouldst not play false, and yet wouldst wrongly win: thou'dst have, great glamis, that which cries, "thus thou must do, if thou have it: and that which rather thou dost fear to do than wishest should be undone." hie thee hither, that i may pour my spirits in thine ear; and chastise with the valor of my tongue all that impedes thee from the golden round, which fate and metaphysical aid doth seem to have thee crown'd withal.  

he lacks ambition.  

he is hesitant.  

he lacks courage.  

he has moral scruples.

c) by giving an example of how mary beth tinker did, in fact, disrupt her mathematics class

explanation:

petitioner john f. tinker, 15 years of age, and solicitor christopher eckhardt, 16 years of age, went to secondary schools in des moines, iowa.