The correct sequence regarding base strength of aliphatic amines in aqueous solution is:
A. `R_(3)N gt R_(2) NH gt RNH_(2) gt NH_(3)`
B. `R_(2)NH gt RNH_(2) gt R_(3)N gt NH_(3)`
C. `R_(2)NH gt R_(3)N gt RNH_(2) gt NH_(3)`
D. `RNH_(2) gt R_(2)NH gt R_(3)N gt NH_(3)`