Low-level wind shear are sudden changes in wind speed and/or wind direction up to altitudes of 1600 ft (500 m) above-ground is a hazardous meteorological phenomenon in aviation. It may radically change the aerodynamic circumstances of the flight, particularly the critical phases of flight - during the final approach path and landing, take-off and initial climb-out flight paths - and consequently, it may threaten human lives and the health of passengers, people at the airport and its surrounding areas.

Note: It seems that there are multiple possible answers for this question, including "inversion". However, since we have no info that may indicate the presence of an inversion, we believe that the examiner is looking for "low level windshear".

Further information on windshear:
Windshear Recognition
Timely recognition of a windshear condition is vital for the successful implementation of the windshear recovery/escape procedure. The following deviations should be considered as indications of a possible windshear condition:

• Indicated airspeed variations in excess of 15 kt
• Ground speed variations
• Analog wind indication variations: Direction and velocity
• Vertical speed excursions of 500 ft/mn
• Pitch attitude excursions of 5 degrees
• Glide slope deviation of 1 dot
• Heading variations of 10 degrees
• Unusual autothrust activity or throttle levers position.