The Thermoacidophile Sulfolobus Acidocaldarius Lacks Peptidoglycan, but Still Possesses a Cell

The thermoacidophile Sulfolobus acidocaldarius lacks peptidoglycan, but still possesses a cell wall. What is likely to be true of this species?
1) It is a bacterium.
2) It is an archaean.
3) The optimal pH of its enzymes lies above pH 7.
4) The optimal pH of its enzymes lies below pH 7.
5) It could inhabit certain hydrothermal springs.
6) It could inhabit alkaline hot springs.

A) 1, 3, and 6
B) 2, 4, and 6
C) 2, 4, and 5
D) 1, 3, and 5
E) 1, 4, and 5