Each of A, C, and D are rational, so presumably B is the answer here.
A is rational, since [tex]10\times0.3=3[/tex], so [tex]0.3=\dfrac3{10}[/tex].
C is also rational. If [tex]x=0.777\ldots[/tex], then [tex]10x=7.777\ldots[/tex]. This would mean [tex]10x-x=9x=7[/tex], and so [tex]x=\dfrac79[/tex].
D is rational by a similar argument. If [tex]x=0.4545\ldots[/tex], then [tex]100x=45.4545\ldots[/tex]. So, [tex]100x-x=99x=45[/tex], which means [tex]x=\dfrac{45}{99}=\dfrac5{11}[/tex].
