Choose between the two options to answer the question specified in the brackets for the following:

Choose between the two options to answer the question specified in the brackets for the following:

An example is illustrated below.

Example: Corolla or Calyx (Which is the outer whorl?) Answer: Calyx

(i) Blood in the renal artery or renal vein (Which one has more urea?)

(ii) Perilymph or endolymph (Which one surrounds the organ of Corti?)

(iii) Lenticels or stomata (Which one remains open always?)

(iv) Sclerotic layer or choroid layer (Which one forms the Iris?)

(v) Blood in the pulmonary artery or pulmonary vein (Which one contains less oxyhaemoglobin?)