The right answer is figure 4
To find parallel lines, the two lines connecting them (AB and AC) must be consistent with each other. You can determine this consistency by dividing the top number by the bottom number (AD by DB, AE by EC respectively). If the lines are consistent with each other, the result you get from division will be the same. This is true for figure 4 (5.5 / 15 = 0.3666, 6.6 / 18 = 0.3666), but not for the others. So you have your answer.