Assertion: Pinus shows formation of annual rings.
Reason: Pinus grows in area of environmental fluctuation.

Options

A. If both the assertion and the reason are true and the reason is a correct explanation of the assertion
B. If both assertion and reason are true but the reason is not a correct explanation of the assertion
C. If the assertion is true but the reason is false
D. If both the assertion and reason are false

Answer

a

Explanation

Secondary growth takes place in the manner similar to dicotyledonous stem. The secondary word showws well marked growth rings which are formed annually due to environmental fluctuations. Each annual ring possesses a zone of spring and an autumn wood. Spring wood is formed during season under availability of enough water and minerals it possess large polygonal, thin walled and wide tracheids with large brodered pits. Autumn wood is formed during Authumn season. It possesses smaller squrish, thick walled and narrow tracheids with small bordered pits. it is evident that the size of tracheids shows a marked variation with regard to amount of nature available in the respective season.