Given the figure below, what is the missing step in Pam's proof that the sum of the measures of the Interior angles of a triangle is 180°?
please i need help, there’s 80 points if you help

Option (3) from the top.

Step-by-step explanation:

                     Statements                      Reasons

1). m∠1 + m∠2 + m∠3 = 180°   1). The angles form a line

2). m∠A = m∠2                       2). Alternate interior angles are equal.

3). m∠3 = m∠B                       3).Because corresponding angles are equal.  

4). m∠1 + m∠A + m∠B = 180° 4). Substitution

Hence, sum of the interior angles of a triangle is 180°.

Therefore, option (3) from the top will be the correct option.

c. side angle side. u shares the same sides