Alarge portion of precipitation in the rainforest occurs as a result of a. perspiration b. respiration c. oxidation d. transpiration

D)Transpiration

Transpiration can be defined as the process in which moisture is carried through the plants from the roots to the small pores on the underside of leaves where it changes to vapor and released to the atmosphere. Thus, transpiration contribute to the loss of moisture in the upper soil zone and this usually have effect on the vegetation. However, the process of transpiration depends largely on weather conditions such as humidity, sunlight availability soil type and saturation.

d. transpiration

Explanation: Plants and trees are the organisms which contributes to the water cycle of the nature by undergoing a process that is called as transpiration. The transpiration is a process through which the plants loose the excess amount of water that is not required by them to their external environment. The water lost in the form of water vapor accumulates in the atmosphere which on condensation forms the clouds which when further cool down results in precipitation.  

the sugar-phosphate backbone forms the structural framework of nucleic acids, including dna and rna. this backbone is composed of alternating sugar and phosphate groups, and defines directionality of the molecule.