Final answer:
The secure identifier for transmitting credit card information online is HTTPS, which stands for HyperText Transfer Protocol Secure.
Step-by-step explanation:
The identifier that indicates the connection is secure for transmitting credit card information to a website is HTTPS. HTTPS stands for HyperText Transfer Protocol Secure and is the secure version of HTTP. When you see HTTPS at the beginning of a web address, it means that all communication between your browser and the website is encrypted, making it much harder for anyone else to intercept and read the data.