No-arbitrage band

An arbitrage desk borrows at $r_b = 7.00\%$ and lends at $r_\ell = 5.25\%$. Its all-in round-trip cost for the cash basket plus futures is $c = 0.25\%$ of spot, charged at inception. Use $q = 1.42\%$ and the Dec contract (54 days). (a) Compute the no-arbitrage band (7.5) for the Dec future. Is 24,719.10 inside it? (b) What is the largest $c$ for which a Dec price of 24,800 would allow a cash-and-carry arbitrage for this desk? (c) Explain why the lower edge of the band is, in practice, enforced mainly by holders of the stocks rather than by short sellers in India.