The correct option is (c) (i), (iii) and (iv) are correct.
Explanation:
(i) Its state is changed from liquid to semi solid:
When milk turns into curd, it becomes semi-solid, which is a true statement.
(ii) It changes colour:
This statement is not true; the color of milk usually does not significantly change when it becomes curd.
(iii) It changes taste:
Yes, the taste of milk changes drastically when it turns into curd due to the formation of lactic acid.
(iv) The change cannot be reversed:
This is also true, as converting curd back into milk is not a simple process and requires additional procedures.
Why other options are incorrect:
(a) (i) and (ii) are correct: This option is incorrect because the statement about color change is not true.
(b) (ii) and (iii) are correct: This option is incorrect as the color change statement is false.
(d) (i) to (iv) are correct: This option is incorrect because the statement about color change is false.