What is the mass number if the isotope lithium -7

The correct option is;

The sum of angles A and B are supplementary to angle C

Step-by-step explanation:

The statements are analysed as follows

1. Angle A is congruent to itself reflective property

Which shows that ΔABC and ΔADE have a common and equal angle

2. Segment ED and CB are parallel

From the transversal line passing EB and CB which shows that the angles ∠ADE and ∠ABC are equal and also ∠AED and ∠ACB are equal

The statement is used to prove similarity between the ΔABC and ΔADE

3. The sum of angles A and B are supplementary to angle C

The above statements relates to only ΔABC and i does not show similarity between ΔABC and ΔADE.