Annual rings are produced due to the activity of:

In dicot roots,which tissues die due to the activity of the cork cambium (phellogen)?

Vascular cambium of the root is an example of

The cork cambium,cork and secondary cortex are collectively called

$A$ $100$-year-old tree which shows well-marked annual rings in its trunk will have:

$I.$ Annual rings are formed as a result of seasonal environmental conditions.
$II.$ Tracheids/vessel elements are larger during periods when water is abundant.
$III.$ Tracheids/vessel elements have thicker walls during periods of water deprivation.
$IV.$ Wood formed in previous years is always darker than newer wood.
Select the combination of correct statements from the options given below.