const prices = {"apple":[{value:3,desc:"Apple 1kg 3€"},{value:5,desc:"Apple 2kg 5€"},{value:7,desc:"Apple 3kg 7€"}],
"banana":[{value:3,desc:"Banana 2kg 3.5€"},{value:5,desc:"Banana 4kg 7€"},{value:7,desc:"Banana 5kg 11€"}],
"peach":[{value:3,desc:"Peach 1.5kg 3€"},{value:5,desc:"Peach 3kg 6€"},{value:7,desc:"Peach 4kg 7€"}]}
const price = document.querySelector('[name=price]');
document.querySelector('[name=fruit]').addEventListener('change', function(e) {
price.innerHTML = prices[this.value].reduce((acc, elem) => `${acc}<option value="${elem.value}">${elem.desc}</option>`, "");
});
<select name="fruit">
<option value="apple">Apple</option>
<option value="banana">Banana</option>
<option value="peach">Peach</option>
</select>
<br />
<select name="price">
<option value="3">Apple 1kg 3€</option>
<option value="5">Apple 2kg 5€</option>
<option value="7">Apple 3kg 7€</option>
</select>