Q1: On which of the following voltage range settings will a voltmeter present the minimum load on a circuit?

ANS:D - 1,000 V

@All.

A voltmeter's setting is made in terms of Ohm/V.

So, for sensitive circuits, the voltmeter will draw minimum current when its resistance is maximum which will be for V=1000V available in options.

For example, if Voltmeter sensitivity is 1000 Ohm/V then for 1000 Volt, its resistance will be 1000 * 1000 = 1000000 Ohm and it will draw negligible current.
That's it.