Flask how to specify a default value for select tag HTML

Current carrier: {{ appt.carrier }}
Option to select a new carrier:


    {% for carrier in carriers %}
        
        {{ carrier.carrier_name }}
    {% endfor %}

from flask import Flask, render_template, flash, url_for, request, redirect

app = Flask(__name__)
app.secret_key = b'a secret key'


@app.route('/update', methods=['GET', 'POST'])
def show_update():
    current_carrier = "tello"
    carriers = [{"carrier_name": "mint"},
                {"carrier_name": "tmobile"},
                {"carrier_name": "tello"}]
    return render_template('update.html', current_carrier=current_carrier,
                           carriers=carriers)

    
    


Current carrier: {{ current_carrier }}
Option to select a new carrier:


    {% for carrier in carriers %}
    
        {{ carrier.carrier_name }}
    
    {% endfor %}