$A.45\%\cdot 200\text{m}=\frac{45}{{\sout{100}}^1}\cdot {\sout{200}}^2\text{m}=45\cdot 2\text{m}=90\text{m}$     

$\underline{\underline{B.}}1,5\%\cdot 40\text{kg}=\frac{1,5}{100}\cdot 40\text{kg}=\frac{15}{100\sout{0}}\cdot 4\sout{0}\text{kg}=\frac{15}{100}\cdot 4\text{kg}=\frac{60}{100}\text{kg}=0,6\text{kg}\ne 6\text{kg}$     

$C.0,3\%\cdot 150\text{l}=\frac{0,3}{100}\cdot 150\text{l}=\frac{3}{100\sout{0}}\cdot 15\sout{0}\text{l}=\frac{45}{100}\text{l}=0,45\text{l}$      

$D.125\%\cdot 120\text{zł}=\frac{125}{100}\cdot 120\text{zł}=\frac{5}{{\sout{4}}^1}\cdot {\sout{120}}^{30}\text{zł}=5\cdot 30\text{zł}=150\text{zł}$  

Poprawna odpowiedź to: B.