Does anyone know the answer

Answer:
[tex]\frac{4.2}{2.8}[/tex]
Step-by-step explanation:
since [tex]\frac{a}{b}[/tex] is proportional to [tex]\frac{2.1}{1.4}[/tex], then look at the answer choices.
I noticed the second option [tex]\frac{4.2}{2.8}[/tex] is the answer because if you multiply by 2 you get this answer