What were developed in the latter half of the 20th century to
overcome the force of gravity to reach orbital velocities?

step-by-step explanation:

options a,b,c are the right answer.

step-by-step explanation:

a linear parent function is always represented as y = x

if we write this function in the form of y=mx+c

⇒

or  

now if we plot a graph we will find these characteristics:

1) y intercept of the graph is zero so its a straight line passing through origin.

2) as we can see in both the forms of function written, values of x and y may be either positive or negative for the positive slope means points on the graph are either in first quadrant or in third one.

3) it's slope is one.

there is no grid

step-by-step explanation:

make sure you have version 2.50

try looking in the very back of the book : )

step-by-step explanation:

you can download it here