Why does convergence means smaller angles?

[amit1982]

Hello.
can you help me understand the solution?

It's a GRE math problem where we need to determine which quantity is greater. I'm attaching the question diagram.

The answer is A, i.e a+b > 180 . Here is the book's explanation : "Since lines 1 and 2 intersect to the left of the diagram, they are not parallel. As they converge, the angles closer to them become smaller. Thus a > c, and b > d. Since a and c are supplementary and b and d are supplementary, a and c must each be greater than 90. Thus their sum must be greater than 180 "

I would appreciate any help figuring out why does a > c ? How can we infer this ?
Thank you so much.

Source: page 377 of GRE, McGraw Hill, Ninth Edition (2023) / Erfun Geula