This is challenging. this will definitely prove that you are

y = 2x + 13

Positive value:

2x + 13 > 0

2x > -13

x > -6.5

Negative value

2x + 13 < 0

2x < -13

x < -6.5

y=2x+13

y>0 would be a positive value

2x+13>0

subtract 13 from each side

2x >-13

divide by 2

x > -13/2

x > -6 1/2

y < 0 is a negative value

2x+13 < 0

2x<-13

x < -13/2

x < -6 1/2

if x > -6 1/2  it has a positive value

if x< -6 1/2 it has a negative value

x= -6 1/2  it equals 0

step-by-stp

the correct answer is the section c

plants store their excess carbohydrate in the form of starch so that it could be used as energy source later on. the excess carbohydrate is converted into starch in the plastid i.e. chloroplast & this process occurs in the presence of sunlight. it is an insoluble polymer of glucose which gets stored in cell organelles named as amyloplasts. in some plants, starch is also stored in roots and embryos.