Questions

If some action has started in the past and is still continuing, then present perfect continuous tense should be used instead of present continuous tense. So, the phrase ‘am waiting’ needs to be replaced with ‘have been waiting’ to make the sentence contextually correct. Thus, the correct formation would be, ‘I have been waiting for three –quarters of an hour’.

‘Regret for’ needs to be replaced with ‘regret’ to make the sentence grammatically correct. This is because ‘regret’ is not followed by a preposition. Thus, the correct formation would be, ‘I regret using objectionable words against a man so mighty’.

Here from the above options, Algae is an Autotroph.

Autotrophs : 

An Autotroph is also called as Producer, is an organism that produces complex organic compounds from simple substances present in its surroundings, generally using energy from light or inorganic chemical reactions.

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