Consider:
TRANSFORM First(Data.Cat) AS FirstOfCat
SELECT Data.ID, Data.Name
FROM Data
GROUP BY Data.ID, Data.Name
PIVOT "Cat" & DCount("*","Data","ID=" & [ID] & " AND Cat<'" & [Cat] & "'")+1;
Or if there is a unique record identifier field – autonumber should serve:
TRANSFORM First(Data.Cat) AS FirstOfCat
SELECT Data.ID, Data.Name
FROM Data
GROUP BY Data.ID, Data.Name
PIVOT "Cat" & DCount("*","Data","ID=" & [ID] & " AND ID_PK<" & [ID_PK])+1;