what technique can be used to minimize the impact of a scan on a table’s provisioned throughput?

I choose D

Answer is A see this
http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/QueryAndScan.html

A parallel scan with a large number of workers can easily consume all of the provisioned throughput for the table or index being scanned. It is best to avoid such scans if the table or index is also incurring heavy read or write activity from other applications.

To control the amount of data returned per request, use the Limit parameter. This can help prevent situations where one worker consumes all of the provisioned throughput, at the expense of all other workers. For more information, see “Reduce Page Size” in Avoid Sudden Bursts of Read Activity.

a

A

Instead of using a large Scan operation, you can use the following techniques to minimize the impact of a scan on a table’s provisioned throughput.

Reduce Page Size
Because a Scan operation reads an entire page (by default, 1 MB), you can reduce the impact of the scan operation by setting a smaller page size. The Scan operation provides a Limit parameter that you can use to set the page size for your request. Each Scan or Query request that has a smaller page size uses fewer read operations and creates a “pause” between each request. For example, if each item is 4 KB and you set the page size to 40 items, then a Query request would consume only 40 strongly consistent read operations or 20 eventually consistent read operations. A larger number of smaller Scan or Query operations would allow your other critical requests to succeed without throttling.

A