The length of time that a slide appears before automatically advancing to the next slide can be set in the A. Timing group under the Transitions tab.
B. Transition to This Slide group under the Transitions tab.
C. Timing group in the Master Slide view.
D. Transition to This Slide group in the Master Slide view.

A.

Explanation:

The transition time between slides can be specified in a presentation. The duration of transition can be set by going to the 'Transitions Tab' then in 'Timing Group/Section'. In the timing group, duration can be increased or decreased, as per the desire. The time is set in seconds in duration section.

So, the length of time between two slides can be changed by going to the 'Timing group' under the 'Transitions Tab'.

Therefore, option A is correct.

so much for the extra points :

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