Which agent of erosion produced many of the large parallel grooves and scratches seen in surface bedrock across New York State?

The agent of erosion that produced many of the large parallel grooves and scratches seen in surface bedrock across New York State is glaciers.

Here's the step by step explanation:

1. Glaciers are large, slow-moving masses of ice that have the ability to erode or wear away the land beneath them.

2. As glaciers move, they pick up rocks and other debris from the ground. This debris gets trapped in the ice and is dragged along as the glacier moves.

3. This process is known as glacial plucking. The rocks and debris trapped in the glacier scrape against the bedrock, creating large parallel grooves and scratches.

4. During the last Ice Age, much of New York State was covered by a large glacier. As this glacier moved, it scraped against the bedrock, creating the grooves and scratches that we see today.

5. Therefore, the large parallel grooves and scratches seen in surface bedrock across New York State are the result of glacial erosion.