GMAT Reading Comprehension (RC) | Re: Before the early eighteenth century, forms of communication

I disagree with #3 answer.
Here is why: "Within only a few years, the mixture of French Sign Language with Home Sign had reached equilibrium and was taught in other institutions for the deaf as American Sign Language." Reaching equilibrium doesn't constitute that it was equally important. For instance, French SL could have influenced it 90% and Home sign influenced it 10%, an equilibrium would still be reach - though both are not equally important.

Please comment.