The correct answer is A. Southern Europe has a large number of mountains, while northeastern Europe is mostly flat.
Step-by-step explanation:
In geography, the elevation of the land surface is called terrain or relief, this geographical concept in most cases is related to the existence of mountains and valleys that made the surface elevation vary. Additionally, it is common in maps the relief is represented by marking zones with high elevation in yellow or orange while zones with low elevation are marked in green, this is the case of the map presented in the question in which low elevations zones from 0 to 499 meters are represented in green while high elevation zones from 500 to 2000 meters or more are represented using yellow and orange.
In terms of elevation of land surface or relief, this map reveals northeastern Europe which includes countries such as Rusia, Ukrania, Poland or Lithuania has few elevation zones as almost all the zone is represented in green, while the south of Europe including countries such as Italy, Spain, Portugal or France has a lot of zones with high elevation as some sections have been represented in yellow or orange. Considering this, it can be concluded the map shows "Southern Europe has a large number of mountains, while northeastern Europe is mostly flat" because in Southern Europe is common to find elevations that are higher than 500 m. which is classified as high and shows there are a lot of mountains, while in northeastern Europe the elevation is lower than 500 m. which shows in there the surface is flat or that there are mainly valleys.