I went through this question as following; - Wild type sequence is RKMYI. This wild type has +1 as a net charge at pH 7 - XI sequence is GDDCM. This wild type has -2 as a net charge at pH 7 But, I'm still confused why is choice "D" the correct answer ?

Table 1 Variants of LipA Compared to the wild-type LipA, what is the change in net charge in variant XI at pH 7? A. +4 B. +3 C. 3 D. 4