path_to_your_php_script.php

<?php
// Check if the form is submitted
if ($_SERVER["REQUEST_METHOD"] == "POST") {
    $errors = [];

    // Validate Quantity
    if (empty($_POST['quantity'])) {
        $errors[] = "Please select a quantity.";
    }

    // Validate Size (at least one size should be selected)
    if (empty($_POST['size'])) {
        $errors[] = "Please select at least one size.";
    }

    // Validate Option (Egg or Eggless should be selected)
    if (empty($_POST['option'])) {
        $errors[] = "Please select an option (Egg or Eggless).";
    }

    // If there are no errors, process the data (example: add to cart, redirect, etc.)
    if (empty($errors)) {
        // Process the form data, e.g., redirect to checkout or save to database
        header("Location: checkout.php");  // Example: Redirect to checkout page
        exit;
    } else {
        // Display errors if any
        foreach ($errors as $error) {
            echo "<p style='color: red;'>$error</p>";
        }
    }
}
?>