Answer:
A. Houston and Central Texas
Step-by-step explanation:
The railroad line's construction which made progress in Texas during the Civil War years are Houston and Central Texas.
Houston and Central Texas railway which is known with the acronym (H&TC) is presently known as Union Pacific Railroad. The construction commenced in January 1, 1853 with an 872 mile railway system. By April 22, 1861 the construction of the railroad has reached 81-miles which is 130km point at Millican.
The construction of the railroad was halted in the year 1867 because of the Civil war and construction resumed when the war came to an end