How to convince my parents to let me go to prom?

I'm almost 16. My first prom is in a few months, but the payment is due this month. My parents are your typical, conservative Indian & Christian parents. How do I persuade them to let me go? They hate me hanging around boys, but I go to a girls school. The boys school is attending, but I know no one in my year, and I also intend on going with my friends.

They're worried about drugs, since they've heard from an older boy that goes to the other school that he didn't go since he heard about the drugs at his prom.

I know at the moment this seems like an unmovable decision, but are there any fair arguments that might be able to sway them slightly?

( Yes, I know after parties are off the table. Yes, I'm slightly upset. )
Updates
+1 y
My mum's swayed, but my dad's hellbent on, 'getting my life to a secure point', before anything like this. At least I tried, thank you so much for the help though! xo
How to convince my parents to let me go to prom?
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