Refer to figure.
WAKE TURBULENCE

Whenever an aeroplane generates lift, air spills over the wing tips from the high pressure areas below the wings to the low pressure areas above them. This flow causes rapidly rotating whirlpools of air called wingtip vortices. An aircraft generates vortices from the moment it rotates on take-off to touchdown.

Looking at the answer options:

Departing from a crossing runway after another aircraft rotated beyond the intersection --> CORRECT. If the departing aircraft has rotated beyond the crossing intersection, then no vortices are created until already past your runway. The take-off roll and climb will be clear of wake turbulence.

When crossing behind and 500 ft below a departing aeroplane in light wind conditions --> INCORRECT. Vortices descend over time, so being behind and below would put your aircraft in any wake turbulence.

Landing on crossing runway after another aircraft rotated prior the intersection --> INCORRECT. The departing aircraft rotated prior to the intersection and so was generating vortices which lie over your landing runway.

Departing from a parallel runway (600 m apart) downwind of another aeroplane, which has executed a low missed approach --> INCORRECT. An aircraft performing a go around will create strong wake turbulence as it is at low speed and high angles of attack. Being downwind on a parallel runway would be dangerous as the wind will push the vortices towards your flight path.