With working with scientific notation questions

1).  ' E+12 ' means ' move the decimal point 12 places that way ==> '.
When you do that to  8.6  you end up with the number in choice-A.

 2).  Same process.  When you do that same thing to choice-B,
you end up with 135,000,000,000,000 .

3).  1 g = 1,000 mg
     60 sec = 1 minute

(5.8 x 10⁶ mg/s) x (1 g/1,000 mg) x (60 sec/min) =

(5.8 x 10⁶ x 1 x 60 / 1,000) (g/min) =

 0.348 x 10⁶ g/min  =  3.48 x 10⁵ g/min

4). 3 feet = 1 yd
     365 day = 1 year

(5.6 x 10⁻³ yd/year) x (3 feet/yd) x (1 year/365 day) =

(5.6 x 10⁻³ x 3 x 1 / 365) (feet/day) =

       0.04603 x 10⁻³  =  4.603 x 10⁻⁵ ft/day

5).  365 days = 1 year

(2.6 x 10² lb/year per tree) x (3.9 x 10¹¹ trees) x (1 year/365 days) =

(2.6 x 10² x 3.9 x 10¹¹ / 365) (lb/day)  = 

     0.0278 x 10¹³  lb/day = 2.78 x 10¹¹ lb/day