Choose an appropriate preposition to complete the sentence.
After months of healthy eating, she allowed herself to indulge _____ a slice of pizza.

Indulge in: 
English Meaning - To allow yourself or another person to have something enjoyable, especially more than is good for you.
Bangla Meaning - উপভোগ করার স্বাধীনতা নেওয়া; (নিজেকে) প্রশ্রয় দেওয়া; সাধ মেটানো। 
Example - He never indulged in the luxury of good wines.

Source: Cambridge Dictionary & Accessible Dictionary by Bangla Academy.