Fill in the blank with the phrase that makes the proof statement true.

Given that angle 1 is congruent to angle 3 and that _ because vertical angles are congruent.

A. the two lines bisect each other
B. angle 1 is congruent to angle 4
C. angle 2 is congruent to angle 3
D. the two lines are perpendicular

Assume that there is a 11% rate of disk drive failure in a year. a. if all your computer data is stored on a hard disk drive with a copy stored on a second hard disk drive, what is the probability that during a year, you can avoid catastrophe with at least one working drive? b. if copies of all your computer data are stored on four independent hard disk drives, what is the probability that during a year, you can avoid catastrophe with at least one working drive?