Table:
0
A
B
C
D
E
F
1
Building
Height [m]
Floors
Built
City
Architect
2
Eaton's Department Store *
46
9
1904
Winnipeg
John Woodman
3
Union Bank Tower
48
10
1904
Winnipeg
Darling and Pearson
4
Lindsay Building
44
11
1911
Winnipeg
Woodman and Carey
5
Confederation Building
46
12
1911
Winnipeg
J. Wilson Gray
6
National Bank Building
50
13
1911
Winnipeg
John D. Atchison
7
Electric Railway Chambers
45
12
1912
Winnipeg
Pratt and Ross, Charles S. Frost
8
Hotel Fort Garry
59
14
1913
Winnipeg
Ross and MacFarlane
9
Marlbourgh Hotel
42
10
1913
Winnipeg
J. Chisholm & Son
10
Paris Building
42
11
1915
Winnipeg
Woodman and Carey
11
Bank of Hamilton Building
45
10
1916
Winnipeg
John D. Atchison
12
Manitoba Legislative Building
79
5
1920
Winnipeg
Simon and Boddington

Questions and formulas:
Question: Who was the architect that built the Electric Railway Chambers before 1915?
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:F1,(D1<1915)*(A1="electric railway chambers")),6))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:F12,(D2:D12<1915)*(A2:A12="electric railway chambers")),6))
Level: medium