Answer:
C)T
Explanation:
The period of a mass-spring system is:

As can be seen, the period of this simple harmonic motion, does not depend at all on the gravitational acceleration (g), neither the mass nor the spring constant depends on this value.
inverted, real, behind the lens is the answer
The wrong type of lens-Microscope, concave
Explanation:
A microscope Basically uses t<u>wo convex lenses to magnify an object, or specimen.</u>
There are 2 lenses in a microscope
- <u>Object Lens:</u>The lens that is closer to the object
- <u>Eyepiece:</u>The lens that is closer to the eye
Both the object lens and the eyepiece, is a convex lens.
The best frequency should be 70 Hz you simply find the difference between 280 Hz and 210 Hz
Power = 
Delilah: 170J/30s = 5.66 W
Adam: 260J/20s = 13 W