The most significant achievement in surveillance of the enemy land forces was provided by
O Airplanes
O Submarines
O Phone Taps
O Double Agents

O Airplanes

Explanation:

Airplanes provided the most significant surveillance of the enemy land  forces because through aeroplane we can see all the activities carried out by enemies against us. There are certain devices and instruments which can be installed on the aeroplane in order to collect data about the surveillance of the enemy land  forces when the airplanes passes over the area of the enemies.

the growing interconnectedness of the world through communication, trade, and the exchange of ideas is an important theme in the history of the 20th and 21st centuries.

explanation:

we need the map to answer the question