Distinguish a landscape name from an administrative unit.
Mecklenburgische Seenplatte is also known as a landscape. Here, however, the question specifically says Landkreis: a territory with a county administration and county council. The present county was formed in 2011, and Neubrandenburg is its county town.
Its official website provides practical services such as waste information and the public health office. These responsibilities make this administrative level visible in daily life. The county and the individual towns or municipalities within it each have their own responsibilities.

The other three answers
The other counties belong to different federal states.
Prignitz
Prignitz is in north-western Brandenburg. It is not a county of Mecklenburg-Vorpommern.
Vogtlandkreis
Vogtlandkreis is in Saxony. The landscape name Vogtland must not be confused with Mecklenburgische Seenplatte.
Rhein-Sieg-Kreis
Rhein-Sieg-Kreis is in North Rhine-Westphalia, in the area around Bonn. It does not belong to Mecklenburg-Vorpommern.
A county town is not the same as a state capital.
Neubrandenburg is this county’s administrative town. Schwerin is the capital of the whole federal state. These functions belong to different levels and must not be interchanged.
Tourism regions and legal county boundaries need not coincide. The answer concerns the official county, rather than every use of its name in a travel guide.
County town: Neubrandenburg · Mecklenburgische Seenplatte county ↗Mecklenburgische Seenplatte → Mecklenburg-Vorpommern.
Also remember Neubrandenburg as the county town; Schwerin remains the state capital.
Three words for this question
- der Landkreiscounty
- A local territorial unit containing several places.
- die Kreisstadtcounty town
- The town where the county administration is based.
- die Zuständigkeitresponsibility / remit
- The matter for which a particular authority is responsible.
