সঠিক উত্তর হচ্ছে: North Atlantic warm currents flow in this region
ব্যাখ্যা:
North Atlantic warm currents flow in this region the ports of Baltic sea opened for trade in winter. Extended Gulf stream current above 40N latitude in Atlantic is termed as North Atlantic Drift, a warm water current, flowing from tropics towards pole affecting climate of near by coastal regions. Hence, sea ports in West Europe between 50N - 60N Latitude remain open in winters also.