What is the most likely reason for using the following model? the object is too small. the object represents a set of data. the object cannot be directly observed. the object represents a prediction about the future.

Option C, The object cannot be directly observed.

Explanation:

The temperature of sun is extremely high due to which it is almost impossible to land on its surface and explore the depth of it. Thus a prototype of it is required to predict its probable internal structure and associated feature which effect our planet "earth".

This prototype/model is based on the deduction arrived after analyzing the  satellite information available in the form of  high resolution images.

Hence, option C is correct

step 1: nitrogen fixation- conversion of atmospheric no₂ into forms useful to plants by lightning, bacteria, and cyanobacteria.

step 2: nitrification-process of converting ammonia to nitrite or nitrate.

step 3: assimilation-plant roots absorb new form of nitrogen.

step 4: ammonification-conversion of organic nitrogen to ammonia by bacteria involved in decomposition.

step 5: denitrification-bacteria turns the decomposed matter back into n₂o, which is released into atmosphere; repeat cycle.