The correct answer to my knowledge would be 45.
Assuming that the 10 soils are each represented by A, B, C, D, E, F, G, H, I, J.
A can combine with 9 others as: AB AC AD AE A F AG AH AI AJ
B can combine as: BC BD BE BF BG BH BI BJ
C as: CD CE CF CG CH CI CJ
D as: DE DF DG DH DI DJ
E as: EF EG EH EI EJ
F as: FG FH FI FJ
G as: GH GI GJ
H as: HI HJ
I as: IJ
Once you add all the combinations together, you get 45.
Hoping this helped you!
Yes, it is okay. you should never change your hypothesis if it was wrong.
<span>A. Carbon dioxide levels have increased
Hope this helps!</span>
<em>A circadian rhythm /sɜːrˈkeɪdiən/ is any biological process that displays an endogenous, entrainable oscillation of about 24 hours. These 24-hour rhythms are driven by a circadian clock, and they have been widely observed in plants, animals, fungi, and cyanobacteria.</em>
the correct answer is a)I only