Which machine learning service can run Tensorflow at scale? a) Cloud AutoML b) AI Platform c) Pre-trained machine learning APIs d) None of the above

The answer is b) AI Platform. Google's AI Platform is designed to run machine learning workloads at scale and it supports TensorFlow, among other popular machine learning frameworks. Here's a step-by-step explanation:

1. Cloud AutoML: This is a suite of machine learning products from Google. It allows developers with limited machine learning expertise to train high-quality models. However, it's not specifically designed to run TensorFlow at scale.

2. AI Platform: This is a development platform that allows machine learning developers and data scientists to build, deploy, and manage machine learning projects. It's designed to run TensorFlow at scale, making it the correct answer.

3. Pre-trained machine learning APIs: These are APIs provided by Google that offer machine learning models which are already trained for specific tasks. They are not designed to run TensorFlow at scale.

4. None of the above: This option would be correct if none of the previous options were designed to run TensorFlow at scale. However, as we've seen, AI Platform is designed for this purpose.