What is the correct order of +I effect of the following groups?
 $a. - {O^ - }, b. - CO_2^ -, c. - CM{e_3}$
 $d. - CHM{e_2}, e. - D, f. - T$
A.a > b > c > d > e > f
B.a > c > d > b > e > f
C.a > c > b > d > f > e
D.a > f > b > d > e > c

Hint: The +I effect, sometimes written as the I effect in literature, is the distance dependent phenomenon by which the charge of a chemical bond affects orientation on adjacent bonds in a molecule, producing a permanent state of polarization. It is described by the electron density when two atoms of two different elements participate in the bond.

Complete step by step answer:
As we know that +I effect is participated in the two different elements. This effect affects stability as well as acidity and basicity of a chemical species. Electronegative atoms draw electrons toward themselves, which can stabilize a conjugate base.
The correct order of +I effect of the following groups is given below,
  $ - {O^ - } > - CO_2^ - > - CM{e_3} > - CHM{e_2} > - D > - T$

Hence, option (A) is the correct answer.

Note: When chemical species donate electrons, it is introducing the carbon chain, the charge is relayed and this effect is called positive inductive effect. This effect is shown at the sigma electron displacement towards the highly negative atom by which one has positively charged and the other one is negatively charged. When the electron releasing character is known as positive inductive effect. This can be expressed by the Hammett equation.