Name the shipper which had the most shipments in first quarter of 1998.
Name the shipper refers to CompanyName; most shipments refers to max(count(OrderID)); first quarter of 1998 refers to ShippedDate = 1998/1 and ShippedDate = 1998/2 and ShippedDate = 1998/3 and ShippedDate = 1998/4
SELECT T1.CompanyName FROM Shippers AS T1 INNER JOIN Orders AS T2 ON T1.ShipperID = T2.ShipVia WHERE STRFTIME('%Y', T2.ShippedDate) = '1998' GROUP BY T1.CompanyName ORDER BY COUNT(T2.OrderID) DESC LIMIT 1