'ताबूत थंड होणे' या वाक्प्रचाराला विरुद्धार्थी वाक्प्रचार ओळखा.

The correct answer is Option D (Avasan chadhane).

Key Points:
• The idiom 'ताबूत थंड होणे' (Tabut thand hone) means enthusiasm dying down, becoming pacified, losing courage, or passion subsiding completely.
• In contrast, 'अवसान चढणे' (Avasan chadhane) means to gain sudden courage, surge with energetic enthusiasm, or be galvanized into spirited action.
• Hence, 'अवसान चढणे' serves as the exact antonymous idiom (विरुद्धार्थी वाक्प्रचार) to 'ताबूत थंड होणे'.
• Meaning of other options: 'तत्त्वज्ञान लंगडे पडणे' means principles proving futile; 'गाशा गुंडाळणे' means packing up and leaving; 'खाका वर करणे' means showing helplessness or having nothing left.
• Key Takeaway: 'ताबूत थंड होणे' means losing enthusiasm, while its opposite 'अवसान चढणे' means being filled with surge of courage.