I. Temperature II.  concentration III. Chlorophyll arrangement IV. Water Among the given factors, identify the external factors that affects the rate of photosynthesis and correct option accordingly
a)	I, II and IV	b)	I, II and III	c)	II, III and IV	d)	I, III and IV

(a)

The external factors would include the availability of sunlight, temperature,  concentration and water. As a plant photosynthesises, all these factors will simultaneously affect its rate.

Hence, through several factors interact and simultaneously affect photosynthesis or  fixation, usually one factor is the major cause or is the one that limits the rate. Hence, at any point the rate will be determined by the factor available at sub-optimal levels