The correct option is C Measurement of growth increase per unit time
Growth can be defined as a permanent or irreversible increase in dry weight, size, mass or volume of a cell, organ or organism. Growth of an organism throughout life has to be compared against a fixed parameter since growth itself is not constant. There are phases where growth is rapid and phases where growth is slow. There are also phases where there is no growth. Cumulatively, all such phases taken into account must be compared against a fixed parameter.
Quantitatively growth can be measured in 2 ways. Absolute growth is the increase in growth or the total growth per unit time. If a graph is plotted for the absolute growth rate, it appears bell shaped. The peak is formed when the growth is fastest.
Relative growth rate is the growth of the organism per unit time, per unit initial growth measured. So here we can see, both the measurements of growth, take ‘time’ into account as a fixed parameter. But relative growth rate takes the initial growth mesured as a parameter additionally.
Growth rate can be determined for increase in size, weight, area
or volume of the plant parts per unit time. The statement that growth rate defines only the height of the plant is incorrect.
Fruits are reproductive appendages of a plant. Number of appendages cannot be defined as the growth rate.
The doubling time takes into account the initial number of cells to begin with and defines relative growth rate.