An organised and differentiated cellular structure having cytoplasm but no nucleus is (a) vessels (b) xylem parenchyma (c) sieve tubes (d) tracheids.
Option C An organised and differentiated cellular structure having cytoplasm but no nucleus are sieve tubes. The sieve tubes are living cells. Their walls are thicker than surrounding parenchyma cells. Sometimes they have a special, shining nacreous thickening. Cytoplasm occurs in the form of thin lining enclosing a big central vacuole.