Which three countries share a vast northern peninsula with russia

Sweden, finland and the norway.

Explanation:

The peninsular of the Russia is also called the Kamchatka peninsula and is as 1,250 km long and it constitutes the Commander and Karaginsky Island groups of the Russian Federation. With about 322,079 ethnic inhabitants and is located in the far east and is adjacent to the pacific sea. The three countries of the Sweden and the Finland and Norway are known as the Scandinavian peninsula of the Eurasian and are located in the northern part and are 1,850 km long and are shard by the Russia.

I'm guessing  a. diverse  because it shows a wide variety of many things.