I have imported a .txt file with four columns into Matlab. Column 1 (x1) and 2 (y1) needed to be plotted against each other and column 3 (x2) and 4 (y2) need to be plotted against each other. Columns 1 and 2 are of the same length. Columns 3 and 4 are of the same length. The length of columns 3 and 4 is shorter than the length of columns 1 and 2. Column 1 (x1) and column 3 (x2) represent time. Column 2 (y1) and column 4 (y2) represent oxygen consumption. Although the lengths are different, they need to be plotted on the same graph. How do I do this in Matlab? (show me the exact code).