Alginic acid is obtained from

Which pigment is present in all algae?

The disease known as "Red rust of tea" is caused by a parasite belonging to which of the following groups?

Match the following classes of algae with their characteristic colours:
$A.$ Cyanophyceae $a.$ Green colour
$B.$ Chlorophyceae $b.$ Blue-green colour
$C.$ Phaeophyceae $c.$ Red colour
$D.$ Rhodophyceae $d.$ Brown colour

Which of the following characteristics is $NOT$ applicable to algae?

The largest unicellular plant,$Acetabularia$,belongs to which of the following groups?