A Music Teacher Had Noticed That Some Students Went to Pieces

A music teacher had noticed that some students went to pieces during exams.He wanted to test whether this performance anxiety was different for people playing different instruments.He took groups of guitarists,drummers and pianists (variable = 'Instru') and measured their anxiety (variable = 'Anxiety') during the exam.He also noted the type of exam they were performing (in the UK,musical instrument exams are known as 'grades' and range from 1 to 8) .He wanted to see whether the type of instrument played affected performance anxiety when accounting for the grade of the exam.Which of the following statements best reflects what the effect of 'Instru' in the output table below tells us?

A) The type of instrument played in the exam had a significant effect on the level of anxiety experienced.
B) The type of instrument played in the exam had a significant effect on the level of anxiety experienced,even after the effect of the grade of the exam had been accounted for.
C) The type of instrument played in the exam did not have a significant effect on the level of anxiety experienced.
D) The type of instrument played in the exam did not have a significant effect on the level of anxiety experienced,even after the effect of the grade of the exam had been accounted for.