Correct Answer: hardly

Solution : The correct answer is option 2.

Explanation:

• - 'Hard' and 'clear' are adjectives.
• - The adverb 'hardly' modifies the verb 'hear'.
• - As a result, to make the phrase grammatically correct, the word 'hardly' should be used.
• - As a result, the right answer is 'hardly'.
• Correct sentence: / could hardly hear her at the back.
• Adverbs are words that modify (describe) a verb (he sings loudly), an adjective (extremely tall), another adverb (ended too fast), or even a whole phrase (Fortunately, I had brought an umbrella).
• - Adverbs frequently end in -ly, however some (such as quick) appear identical to their adjective equivalents.