How did the Texas rail system change it in 1873

Question

a. Refrigerated trains came into use b.Texas rail lines became connected with those of other states c. Tracks were built into the eastern part of the state d. All of the above 

Answer 1

I note that you have submitted this question previously. In this instance, however, you've added the word "it" in the title, and that is an indefinite antecedent (and should not appear in the title).

 

I suggest that you will find the answer in a thorough review of your Social Studies textbook, where this subject matter is taken up.