*$_The rate of heat transfer from a vertical plate by natural convection depends upon the temperature differences (ΔT) between wall and outside bulk. The proportionality is given as?

• A. (≈í√ÆT)1/4
• B. (≈í√ÆT)1/2
• C. (≈í√ÆT)5/4
• D. (≈í√ÆT)3/4