$0.9 \times 12 - 3 \times 3 = 1.8$ 
Mary wanted to buy $12$ lemons. The lemons were sold either for $90$ cents each or at $3$ dollars for a bag of $4$ lemons. How much money would Mary save if she buys three bags of lemons instead of buying $12$ lemons separately? 
Options:
[A] $1.2$ dollars 
[B] $1.5$ dollars 
[C] $1.6$ dollars 
[D] $1.8$ dollars 
[E] $2.1$ dollars 