The correct answer is (c) try hard.
Idiom: 'Fight tooth and nail' / 'Tooth and nail' — means to fight or work with all one's effort and determination; to try very hard using every possible means.
Example: 'She fought tooth and nail to keep her job.'
Bangla meaning: সর্বশক্তি দিয়ে চেষ্টা করা বা লড়াই করা।
Origin: The idiom refers to using both teeth and nails to scratch and bite in a fierce fight — implying maximum effort and desperation.
✗ 'get by heart' — to memorize (মুখস্থ করা).
✗ 'go with heart' — not a standard idiom.
✗ 'get hard' — unrelated.
Source: Cambridge Idioms Dictionary; Oxford Idioms Dictionary.