The compound that cannot have a branched structure is select one:

a. c3h8

b. c4h10

c. c5h12

d. c6h14

C3H8

There is only one isomer of propane:

H H H

HC-C-CH

H. H H

It’s easier to see I’m a bond line formula; however, You can see that trying to take a methyl group off and move it results in the same structure.