Choose the incorrect one from the underlined words in the following sentence. The main results (Fig. 1 and 2) presented by the authors are difficult to follow. For example, how results in Fig. 1 are different compared to Fig. 2 except that the units of effect size are different. Second, if authors have information on species richness differences among studies, why not use those differences as a covariate moderate to explain the variation in effect size which is shown in Fig. 1.

A. For example
B. that
C. Second
D. which