Both (A) and (R) are true ; (R) explains (A)

(i) Remote Sensing refers to the observation and measurement of earthly objects without touching them.
(ii) 'Remote' means far away and 'Sensing' means observing or collecting information.
(iii) Remote sensing means acquiring information of things/places from a distance, using a variety of tools and methods.

Geographers mainly use Chain, Prismatic compass, Plane table, Dumpy level, Abney level, Clinometre, Theodolite, Total Station and GNSS to measure the distance, angle, altitude and position of the area of survey.

(i) A map is the basic tool of a geographer.
(ii) It illustrates the earth's surface clearly and effectively through a combination of drawings, words and symbols.
(iii) Thus, maps form an integral part of teaching geography.
(iv) A map is a location guide.

(i) GPS technology has tremendous applications in everything from mobile phones, watches, bulldozers, shipping containers and ATMs.
(ii) The main purpose of GPS is to help in providing accurate transport data (distance, route and direction).
(iii) It helps in military searches and rescue in wars.
(iv) It can work as a reliable tourist guide.
(v) GPS helps during accident and rescue efforts speeding the delivery of emergency services and disaster relief.
(vi) Weather forecasting, earthquake monitoring and environmental protection can be done effectively by using GPS.