A company wants to build an application that stores images in a Cloud Storage bucket and wants to generate thumbnails as well as resize the images…

Cloud Functions is the most suitable service for this scenario. It is a serverless, event-driven compute platform that executes code in response to events, such as a new file being uploaded to a Cloud Storage bucket. This service is fully managed by Google, requires no server provisioning, and automatically scales based on load, including scaling down to zero. This "scale-to-zero" capability means you only pay for the compute time you consume, making it highly cost-effective and meeting the requirement for minimal effort and automatic scaling.

A. Google Compute Engine: This is an IaaS solution that requires manual management of virtual machines, including scaling and OS patching. It does not automatically scale to zero, incurring costs even when idle.

B. Google App Engine: While it is a managed platform that can scale to zero, it is designed for hosting web applications and APIs, not for single-purpose, event-driven tasks. It is less direct and requires more configuration than Cloud Functions for this specific use case.

D. Google Kubernetes Engine: This is a container orchestration service that provides significant power and flexibility but requires substantial management effort. The underlying cluster nodes do not scale to zero, making it unsuitable for this task's cost and simplicity requirements.

1. Google Cloud Documentation - Cloud Functions Use Cases: The official documentation provides a specific tutorial for this exact use case: "This tutorial demonstrates how to build an event-driven

serverless function to process images. The function is triggered when a file is uploaded to Cloud Storage

and it generates a thumbnail of the image."

Source: Google Cloud

"Tutorial: Cloud Storage trigger: image thumbnailing".

2. Google Cloud Documentation - Choosing a compute option: This document compares Google's compute services. It describes Cloud Functions as ideal for "Event-driven applications that execute code in response to events" and highlights its serverless nature where "you don't need to manage servers or runtimes." In contrast

it positions GCE and GKE as requiring more infrastructure management.

Source: Google Cloud

"Choosing a compute option"

Section: "Serverless computing".

3. Google Cloud Documentation - Cloud Functions Overview: "Cloud Functions is a serverless execution environment for building and connecting cloud services... your function is triggered and your code is executed in a fully managed environment. There is no need to provision any infrastructure or worry about managing any servers." This confirms the "minimal effort" and "managed service" requirements.

Source: Google Cloud

"Cloud Functions - Product Overview".